New strategy to delay food spoilage:Application of new food contact material with antibacterial function

Frequent food poisoning and food-borne diseases outbreaking in recent years have caused people to attach great attention to food safety,especially the food contact materials that are essential in the food industrial chains and daily lives,ensuring their clean sanitation are of great importance in blocking micro-bial contamination and spread of food-borne pathogens.Stainless steel(SS)is one of the most accepted and widely used food contact material,and the Cu-bearing SS possesses excellent antibacterial perfor-mance and maintains the original mechanical properties of SS,maybe making it a better substitute for the conventional SS in the food area.Taking advantages of bactericidal and antifouling properties of Cu-bearing SS,this study simulated a variety of food contact scenarios,explored a new strategy for food preservation and food safety by using Cu-bearing SS as a food contact material.The results showed that the Cu-bearing SS could not only delay the spoilage of different foods by inhibiting the activity of microor-ganisms in foods,but also reduce the expressions of spoilage traits of bacteria as well as the formation of biofilms by quenching the quorum-sensing signals,and further creating a good bacteriostatic atmo-sphere for the contacted food and its surrounding environment.In addition,the remarkable antifouling property of Cu-bearing SS would give the material a self-cleaning feature for food applications,which can avoid secondary contamination of food as a source of contamination.This study well demonstrates that the Cu-bearing SS has broad application potentials and prospects in the food area.     

Study of the interaction between microstructure,mechanical and tribo-performance of a commercial brake lining material

The interaction between microstructure, mechanical, and frictional properties of a commercial brake lining material (BLM) was investigated in order to correlate them to braking performance. For this purpose, a Scanning Electron Microscope (SEM) with energy dispersive X-ray (EDX) mapping and spectrum were used to identify and analyze different constituents. The mechanical properties were determined using compression test. Relevant physical properties (density and porosity) were determined using standard test methods. The friction coefficient and wear behavior of the friction material on contact with the grey cast iron disc were established using a pad-on disc tribometer. The results have shown that the brake lining material contains phenol resin such as the matrix and other various ingredients, including silica, rock and mineral filler reinforcement, barium sulfate and carbon-rich particles as filler and brass particles as friction modifier. It had a varied amount and size up to 1 mm for brass particles. The density and porosity were 1.8 g cm⁻³ and 7%, respectively. The investigated material exhibited excellent mechanical properties in the normal solicitation direction. The average friction coefficient was about 0.65, whereas the friction coefficient was stable. The different actions of various ingredients in terms of their effects on the friction and wear behavior of the BLM could be related to their different bonding strengths with the resin matrix and their different abilities to form friction films (third-body layer) on the surfaces of the material and transfer films on the counterpart cast iron surface in relation to the surface temperature evolution and mechanical properties.     

Active control of nonlinear forced vibration in a flexible beam using piezoelectric material

Geometric nonlinearities of the beam and piezoelectric patch are considered. Velocity feedback control algorithm is implemented applying piezoelectric materials. The equation of motion of the system is established using Hamilton's principle. The effects of control gains on primary resonance properties of the beam are studied. It is observed that, with the amplitude of external excitation increasing, the amplitude of resonance curve increases. The velocity feedback control can improve unstable resonance of the beam. When the control gain is increased to a certain value, the unstable regions in the resonance and amplitude-frequency curves disappear.     

Digital inequality in online reciprocity between generations: A preliminary exploration of ability to use communication technology as a mediator

The current study provides preliminary insights into the disparity between older and younger adults in reciprocity in online social interaction. It also offers a synthesized conceptualization of different levels of online reciprocity that have been varyingly adopted in past research (e.g., presence of communicative response, matching of message length and quality). ANOVA and regression analyses of survey and behavioral data from 502 participants (304 college students and 198 older adults) revealed that, compared to the college student sample, the older adult sample self-reported their online reciprocity as lower and was less likely to reciprocate a stimulus email. Ability to use communication technology predicted all types and measures of online reciprocity and mediated the relationship between age group and online reciprocity. Implications of the findings are discussed in connection to the phenomenon of digital inequality.     

Effect of a variation in material properties on the crack tip opening displacement

This paper investigates the effect of a variation in material properties on the crack tip opening displacement, a parameter often used in the prediction of fatigue and fracture. This situation is typical when a component is subjected to a relatively slow temperature fluctuation or the material properties undergo direct changes, such as due to a phase transformation. An analytical strip‐yield model is developed using the small‐scale yielding assumption and theory of complex potentials. Four cases of crack tip plasticity behaviour are identified for the different combinations of parameters controlling the variation in material properties. Results of calculations over a wide range of material properties are presented and show a significant effect on the crack tip opening displacement. Finite element simulations are conducted to verify the analytical findings. The implications of the outcomes in relation to several practical situations are also discussed.     

The effect of silicon dioxide content of natural stones on their strength properties,material removal rate and power consumption in diamond grinding

The paper addresses the influence of silicon dioxide content of natural stones on their Mohs hardness, ultimate uniaxial compression strength, microhardness as well as on the removal rate and power consumption in diamond grinding of these materials. An increase in the amount of this constituent in natural stones is demonstrated to have an effect on strength properties and power consumption in grinding and a considerable effect on removal rate in diamond grinding.     

A new finite element integration scheme. Application to a simple shear test of anisotropic material

Finite element simulations involving large strains and large displacements imply the setting up of a precise kinematics for the integration scheme. Moreover, anisotropic mechanical behaviours have to be expressed in an appropriate local reference frame. In the present paper, a computational procedure is derived from a particular velocity gradient definition. Its implementation in a finite element code is described. Application to a simple shear test is proposed. For anisotropic materials, a sinusoidal behaviour of the shear stress component is emphasized. This is due to the anisotropic yield locus and appears in the case of a saturated isotropic hardening law. Copyright © 2007 John Wiley & Sons, Ltd.     

Introducing a novel method for materials selection in mechanical design using Z-transformation in statistics for normalization of material properties

Optimum materials selection is a very important task in design process of every product. There are various materials selection methods like Ashby’s method or digital logic methods such as DL and MDL. In the present research work the Z-transformation method is proposed for scaling the material properties to overcome the shortcoming of MDL method. The results show that despite the simple scaling function used, the ranking procedure is as powerful as MDL method and even it is superior to MDL when it ranks the less important materials existing among a list of candidate materials.     

Irreversible growth of a spherical cavity in rubber-like material: A fracture mechanics description

A procedure is presented for determining stress intensity factors for single and double edge cracks in simply supported undamped Bernoulli–Euler beams under a moving load. The approach is based on using modal analysis to determine the equivalent load on the beam, then linear elastic fracture mechanics is used to calculate stress intensity factors (SIF). The results show that SIF is a function of time, speed of the moving load and crack size and location.     

A GA-based method to reduce material handling: the case of TFT-LCD array Fabs in Taiwan

This study proposes a genetic algorithm (GA)-based Material Handling Strategy Function (MHSF) method to increase the productivity of a TFT-LCD array fabrication to improve the traditional FIFO method in TFT-LCD fabrication by the reduction of the material handling for a Rail Guided Vehicle (RGV), because costs of material handling count up to about 50% of production costs. In this article, the MHSF is provided to help material handling commands choice, where a novel GA approach is used to adapt the weights of affecting factors in the function. Finally, to evaluate the performance of the proposed method, experiments using the data from a major TFT-LCD manufacturing plant in Taiwan have been carried out, and the results indicate that it can indeed reduce fabrication time and increase productivity.     

Optimal representation of multi-dimensional random fields with a moderate number of samples: Application to stochastic mechanics

A significant amount of problems and applications in stochastic mechanics and engineering involve multi-dimensional random functions. The probabilistic analysis of these problems is usually computationally very expensive if a brute-force Monte Carlo method is used. Thus, a technique for the optimal selection of a moderate number of samples effectively representing the entire space of sample realizations is of paramount importance. Functional Quantization is a novel technique that has been proven to provide optimal approximations of random functions using a predetermined number of representative samples. The methodology is very easy to implement and it has been shown to work effectively for stationary and non-stationary one-dimensional random functions. This paper discusses the application of the Functional Quantization approach to the domain of multi-dimensional random functions and the applicability is demonstrated for the case of a 2D non-Gaussian field and a two-dimensional panel with uncertain Young modulus under plane stress.     

Nonlinear tensile behaviour of elementary hemp fibres. Part II: Modelling using an anisotropic viscoelastic constitutive law in a material rotating frame

A 3D viscoelastic model is presented, based on the use of finite element method for the study of the nonlinear tensile behaviour of hemp fibres. On the basis of an experimental investigation, Part I of this study (Placet et al., 2014) proposed a scenario based on several physical mechanisms, in order to explain the nonlinear behaviour of such fibres. These mechanisms included viscoelastic strain, cellulose microfibril reorientation, and shear strain-induced crystallisation of the amorphous paracrystalline components. The second part of this ongoing study proposes to implement such mechanisms and the associated constitutive laws in a simplified 3D model, in order to evaluate the contribution of each mechanism to the macroscopic tensile behaviour of the fibre.The results show that the proposed anisotropic viscoelastic constitutive law, describing finite transformations through a material rotating frame formulation, is able to accurately simulate the shape of the experimentally observed tensile curves. This model is also used to investigate the influence of dislocation areas on the tensile behaviour and stress fields.     

Marketing in the material construction of artifacts: A case study of a Portuguese navigation systems company

This article examines the social construction of technological innovations, focusing on how marketers of an information and communication technology (ICT) product interact with engineers in the creation of that product. The main purpose is to develop in empirical terms the concept of “material semiotics' rhetoric”. To this end it takes an in-depth look at a medium-sized Portuguese firm, in which we have over a period of five years observed how a GPS navigation device is generated and developed. We use the notions of “rhetoric” and “frames of reference” in adopting “material semiotics” as the theoretical background for observing the behaviors and interactions of the different actors involved in the construction of this technological artifact. The results show how the rhetorical framework shapes the technology, and also reveals the roles of different professionals when negotiating technical possibilities within the communicational strategies of a firm. The paper highlights the specific role of symbolic aspects in the material development of technology, stressing a relation between rhetoric and material semiotics.     

Scale-up and flow behavior of cohesive granular material in a four-bladed mixer: effect of system and particle size

Flow of cohesive granular materials with different moisture contents was examined in a four-bladed mixer via the discrete element method (DEM). Firstly, the mixer diameter (D) was increased while keeping the particle diameter (d) constant. It was observed that when the mixer diameter to the particle diameter ratio (D/d) was larger than a certain critical size (D/d ≥ 75), granular flow behaviors and mixing kinetics followed simple scaling relations. For D/d ≥ 75, flow patterns and mixing kinetics were found to be independent of system size, and velocities of particles scaled linearly with the tip speed of the impeller blades and particle diffusivities scaled with the tip speed of the blades and mixer diameter. These results suggest that past a certain system size the flow and mixing of cohesive particles in large-scale units can be predicted from smaller systems. Secondly, system size was kept constant and particle diameter was changed and it was observed that by keeping the Bond number constant (by changing the level of cohesion) the flow behavior and mixing patterns did not change, showing that larger particles can be used to simulate flow of smaller cohesive particles in a bladed mixer by matching the Bond numbers.     

From a local community to a global influence. How elBulli restaurant created a new epistemic movement in the world of haute cuisine

Location plays a major role in the building of artistic, technological or scientific movements that emerge in specific locations before achieving a worldwide reach. However, a deeper understanding is needed about the interplay of local/global knowledge dynamics in the epistemic construction of a movement. Based on an in-depth longitudinal study of a critical case, this article sheds light on these issues by analysing the case of ‘techno-emotional cuisine’, a global gastronomic movement initiated and led by chef Ferran Adrià and his team at the restaurant elBulli in Catalonia (in Northern Spain). The results suggest that the dynamics of formation of a new epistemic movement depend on the form and nature of the interactions between the local buzz and global pipelines, and on the capacity of the originating community to develop and diffuse the new rules and ‘episteme’ on a global scale while consolidating them locally.     

From daily movements to population distributions: weather affects competitive ability in a guild of soaring birds

The ability of many animals to access and exploit food is dependent on the ability to move. In the case of scavenging birds, which use soaring flight to locate and exploit ephemeral resources, the cost and speed of movement vary with meteorological factors. These factors are likely to modify the nature of interspecific interactions, as well as individual movement capacity, although the former are less well understood. We used aeronautical models to examine how soaring performance varies with weather within a guild of scavenging birds and the consequences this has for access to a common resource. Birds could be divided broadly into those with low wing loading that are more competitive in conditions with weak updraughts and low winds (black vultures and caracaras), and those with high wing loading that are well adapted for soaring in strong updraughts and moderate to high winds (Andean condors). Spatial trends in meteorological factors seem to confine scavengers with high wing loading to the mountains where they out-compete other birds; a trend that is borne out in worldwide distributions of the largest species. However, model predictions and carcass observations suggest that the competitive ability of these and other birds varies with meteorological conditions in areas where distributions overlap. This challenges the view that scavenging guilds are structured by fixed patterns of dominance and suggests that competitive ability varies across spatial and temporal scales, which may ultimately be a mechanism promoting diversity among aerial scavengers.     

Approximate Analytical Determination of Vibrodiagnostic Parameters of Non-Linearity of Elastic Bodies Due to the Presence of a Closing Crack. Part 2. Determination of Diagnostic Parameters in Principal and 2-nd Order Superharmonic Resonances

Using the constitutive equations derived by the author, variously approximated analytical expressions have been obtained for the determination of principal- and superharmonic-resonance vibrodiagnostic parameters of fatigue damage in the form of a Mode I closing crack in an elastic body. The reliability of the analytical solution is assessed by comparing the calculated and the numerical solution results.     

Detection-Identification of multiple unknown time-dependent point sources in a 2D transport equation: application to accidental pollution

We address the nonlinear inverse source problem of identifying multiple unknown time-dependent point sources occurring in a two-dimensional evolution advection–dispersion–reaction equation. Provided to be available within the monitored domain interfaces for recording the generated state and its flux crossing each suspected zone where a source could occur, we establish a constructive identifiability theorem based on an introduced dispersion-current function that yields uniqueness of the unknown elements defining all occurring sources. Then, the established theorem leads to develop a detection-identification method that goes throughout the monitored domain to detect in each suspected zone whether there exists or not an occurring source. Once a source is detected, the developed method determines lower and upper bounds of the mean value discharged by its unknown time-dependent intensity function. Thereafter, the method localizes the sought position of the detected source as the unique solution of an equation satisfied by the introduced dispersion-current function and identifies its unknown intensity function from solving an associated deconvolution problem. Ultimately, the unknown number of occurring sources is deduced as the sum of all detected-identified active sources. Some numerical experiments on a variant of the surface water BOD pollution model are presented.