Mechanical Properties of Heat-cured Whey Protein-based Edible Films Compared with Collagen Casings under Sausage Manufacturing Conditions

ABSTRACT: Edible films were produced using whey protein isolate (WPI) (5%, w/v), glycerol (3.3%, w/v) and candelilla wax (0.8%, w/v). One set of films was heat cured at 90°C for 12 h and another at 80°C for 24 h. WPI-based films, together with collagen films, were put through a meat-processing scheme typical of Polish sausage manufacture. Meat-processing conditions were stage 1: 57°C/60 min/36% RH; stage 2: 65°C/90 min/60% RH; and stage 3: 77°C/30 min/80% RH. Effects of meat-processing conditions on mechanical properties: tensile strength (TS), elongation (%E), and apparent modulus (AM) were determined. All films remained intact throughout the process. TS, %E, and AM of collagen films did not change during the multistage cooking process. The %E of heat-cured WPI films was similar to that of collagen films and also did not change during the cooking stages. The TS and AM of both heat-cured WPI-based films were initially lower than collagen films and continued to decline during the cooking stages. TS and AM of both films at the end of cooking were lower ( P < 0.05) than films that did not go through the multistage cooking process.     

Trion X+ in vertically coupled type II quantum dots in threading magnetic field

We analyze the energy spectrum of a positively charged exciton confined in a semiconductor heterostructure formed by two vertically coupled, axially symmetrical type II quantum dots located close to each other. The electron in the structure is mainly located inside the dots, while the holes generally move in the exterior region close to the symmetry axis. The solutions of the Schrödinger equation are obtained by a variational separation of variables in the adiabatic limit. Numerical results are shown for bonding and anti-bonding lowest-lying of the trion states corresponding to the different quantum dots morphologies, dimensions, separation between them, thicknesses of the wetting layers, and the magnetic field strength.     

Measurements and Analysis of Fingerprinting Structures for WLAN Localization Systems

Channel‐based radio‐frequency fingerprinting such as a channel impulse response (CIR), channel transfer function (CTF), and frequency coherence function (FCF) have been recently proposed to improve the accuracy at the physical layer; however, their empirical performance, advantages, and limitations have not been well reported. This paper provides a comprehensive empirical performance evaluation of RF location fingerprinting, focusing on a comparison of received‐signal strength, CIR‐, CTF‐, and FCF‐based fingerprinting using the weighted k‐nearest neighbor pattern recognition technique. Frequency domain channel measurements in the IEEE 802.11 band taken on a university campus were used to evaluate the accuracy of the fingerprinting types and their robustness to human‐induced motion perturbations of the channel. The localization performance was analyzed, and the results are described using the spatial and temporal radio propagation characteristics. In particular, we introduce the coherence region to explain the spatial properties and investigate the impact of the Doppler spread in time‐varying channels on the time coherence of RF fingerprint structures.     

Tribological Behavior of Sheet Metal Forming Process Using Acoustic Emission Characteristics

In this study, acoustic emissions (AE) signal processing using wavelet packet transform technique was used to identify damage mechanisms during sheet metal forming simulation experiments. Current investigation was carried out based on decomposing the recorded AE signals into different wavelet levels. Following decomposition process, the energy distribution criteria were used to characterize dominant components, which are considered to be related to dominant damage mechanisms. Results revealed that the energy of AE signals was distributed dominantly on four components, which can be correlated by 3 specific damage mechanisms occurred during simulation experiments. After comparison with previous works, results were validated by surface observations in order to establish a meaningful relation between dominant wavelet components and surface damage mechanisms.     

A strategy for chemical sensing based on frequency tunable acoustic devices

A new acoustic sensor geometry, the magnetic acoustic resonant sensor (MARS), is described. The device comprises a circular 0.5-mm-thick resonant plate fabricated from a wide variety of nonpiezoelectric materials and coated on the underside with a 2.5-microm-thick aluminum film. Harmonic radial shear waves over at least a 2 orders of magnitude frequency range can be induced in the resonant plate by enhanced magnetic direct generation using a noncontacting rf coil and NdFeB magnet. Mass loading with adherent aluminum films produced frequency changes of 106 Hz/nm (40.8 Hz/ng-mm(-2)), while contact with viscous fluids resulted in maximum changes of 15 446 Hz/cP. At an operating frequency of 50 MHz, the device detected viscosity changes as low as 0.0006 cP. The adsorption of proteins such as human IgG and the binding of a complementary antigen, goat anti-human IgG, on the upper nonmetallized surface of the device has been monitored with a detection limit of approximately 75 ng/mL. The binding of substrates and allosteric effectors to glycogen phosphorylase b has provided evidence that the device is very sensitive to viscoelastic changes in adsorbed proteins. The MARS device generates radial shear acoustic waves over a broad bandwidth that are unaffected by the conductivity of the solution. These results suggest that simple metal, glass, crystalline, or polycrystalline plates can be used as a new type of tunable acoustic immunosensor.     

Simple telemedicine for developing regions: camera phones and paper-based microfluidic devices for real-time, off-site diagnosis

This article describes a prototype system for quantifying bioassays and for exchanging the results of the assays digitally with physicians located off-site. The system uses paper-based microfluidic devices for running multiple assays simultaneously, camera phones or portable scanners for digitizing the intensity of color associated with each colorimetric assay, and established communications infrastructure for transferring the digital information from the assay site to an off-site laboratory for analysis by a trained medical professional; the diagnosis then can be returned directly to the healthcare provider in the field. The microfluidic devices were fabricated in paper using photolithography and were functionalized with reagents for colorimetric assays. The results of the assays were quantified by comparing the intensities of the color developed in each assay with those of calibration curves. An example of this system quantified clinically relevant concentrations of glucose and protein in artificial urine. The combination of patterned paper, a portable method for obtaining digital images, and a method for exchanging results of the assays with off-site diagnosticians offers new opportunities for inexpensive monitoring of health, especially in situations that require physicians to travel to patients (e.g., in the developing world, in emergency management, and during field operations by the military) to obtain diagnostic information that might be obtained more effectively by less valuable personnel.     

Acoustic Emission Methodology to Evaluate the Fracture Toughness in Heat Treated AISI D2 Tool Steel

In this article, fracture toughness behavior of tool steel was investigated using Acoustic Emission (AE) monitoring. Fracture toughness (K _IC) values of a specific tool steel was determined by applying various approaches based on conventional AE parameters, such as Acoustic Emission Cumulative Count (AECC), Acoustic Emission Energy Rate (AEER), and the combination of mechanical characteristics and AE information called sentry function. The critical fracture toughness values during crack propagation were achieved by means of relationship between the integral of the sentry function and cumulative fracture toughness (KICUM). Specimens were selected from AISI D2 cold-work tool steel and were heat treated at four different tempering conditions (300, 450, 525, and 575?°C). The results achieved through AE approaches were then compared with a methodology proposed by compact specimen testing according to ASTM standard E399. It was concluded that AE information was an efficient method to investigate fracture characteristics.     

Multi-element probabilistic collocation for sensitivity analysis in cellular signalling networks

The multi-element probabilistic collocation method (ME-PCM) as a tool for sensitivity analysis of differential equation models as applied to cellular signalling networks is formulated. This method utilises a simple, efficient sampling algorithm to quantify local sensitivities throughout the parameter space. The application of the ME-PCM to a previously published ordinary differential equation model of the apoptosis signalling network is presented. The authors verify agreement with the previously identified regions of sensitivity and then go on to analyse this region in greater detail with the ME-PCM. The authors demonstrate the generality of the ME-PCM by studying sensitivity of the system using a variety of biologically relevant markers in the system such as variation in one (or many) chemical species as a function of time, and total exposure of a single chemical species.