John E. Bronlund

Moisture sorption isotherms for crystalline, amorphous and predominantly crystalline lactose powders

Abstract Moisture sorption isotherms for amorphous lactose, crystalline α-lactose monohydrate and a predominantly crystalline lactose powder were measured. No temperature dependence was observed over the range investigated (12–40°C), except for amorphous lactose at 12°C, which absorbed less moisture than observed at higher temperatures. The amount of water absorbed by crystalline powders at high water activity was dependent on the packing density of the powder. This observation could be explained using the capillary condensation theory. The moisture isotherm of a partially amorphous lactose powder was successfully predicted by using a simple additive isotherm model to combine the isotherms of crystalline and amorphous lactose powders. Small quantities of amorphous lactose present on crystalline powders, causes significant changes to the moisture sorption isotherm. If the high water activity region of the isotherm of crystalline α-lactose monohydrate is of interest then the isotherm should be measured at the packing density of interest.

The Role of Oral Processing in Dynamic Sensory Perception

Food oral processing is not only important for the ingestion and digestion of food, but also plays an important role in the perception of texture and flavor. This overall sensory perception is dynamic and occurs during all stages of oral processing. However, the relationships between oral operations and sensory perception are not yet fully understood. This article reviews recent progress and research findings on oral food processing, with a focus on the dynamic character of sensory perception of solid foods. The reviewed studies are discussed in terms of both physiology and food properties, and cover first bite, mastication, and swallowing. Little is known about the dynamics of texture and flavor perception during mastication and the importance on overall perception. Novel approaches use time intensity and temporal dominance techniques, and these will be valuable tools for future research on the dynamics of texture and flavor perception.

Design of a Biologically Inspired Parallel Robot for Foods Chewing

To quantitatively assess food texture changes and/or masticatory efficiency during chewing, the jaw movements and chewing/biting forces must be measured. For this purpose, a robotic solution has been proposed to reproduce the human chewing behavior. The chewing robot of parallel mechanism is based on the biological finding that the mandible is pivoted at the temporomandibular joints and driven by groups of muscles for opening and closing of the mouth. This paper reviews the biomechanics of the mastication system, defines the kinematical mechanism of the chewing robot, and describes the design of the actuation systems. With a linear actuator for a muscle group of mastication, its spatial placement between the mandible or moving plate and the maxilla or ground plate follows the line of action and attachment sites of the muscle. The design requirements for each actuation system are mainly specified as the actuation range, velocity, and acceleration, and the actuation force, which are determined by inverse kinematics analysis via a simulation software and the jaw force analysis via Pythagorean theorem, respectively. A design of the physical linear actuation, which is made up of a rotary motor, a gear reduction train, and a leadscrew, is presented, whereas the challenges are discussed for building the entire chewing robot.

Bond-rupture immunosensors—A review

It has long been the goal of researchers to develop fast and reliable point-of-care alternatives to existing lab-based tests. A viable point-of-care biosensor is fast, reliable, simple, cost-effective, and detects low concentrations of the target analyte. The target of biosensors is biological such as bacteria or virus and as such, the antibody-antigen bond derived from the real immune response is used. Biosensor applications include lab-based tests for the purposes of diagnostics, drug discovery, and research. Additional applications include environmental, food, and agricultural monitoring. The main merits of the bond-rupture method are quick, simple, and capable of discriminating between specific and non-specific interactions. The separation of specific and non-specific bonds is important for working in real-life complex serums such as blood. The bond-rupture technique can provide both qualitative results, the detection of a target, and quantitative results, the concentration of target. Bond-rupture achieves this by a label-free method requiring no pre-processing of the analyte. A piezoelectric transducer such as the quartz crystal microbalance (QCM) shakes the bound particles free from the surface. Other transducers such as Surface Acoustic Wave (SAW) are also considered. The rupture of the bonds is detected as electronic noise. This review article links diverse research areas to build a picture of a field still in development.

Kinematics and Experiments of a Life-Sized Masticatory Robot for Characterizing Food Texture

A life-sized masticatory robot, which is intended to chew foods in a human way while the food properties are evaluated, of a 6RSS parallel mechanism is discussed in this paper. A robotic mechanism is proposed, and its kinematic parameters are defined according to the biomechanical findings and measurements of the human masticatory system. For a given mandibular trajectory to be tracked, the closed-form solution to inverse kinematics of the robot is found for joint actuations, whereas differential kinematics is derived in Jacobian matrices. Major features of the robot, including the motion control system, are presented. Experimental results for free chewing, soft-food chewing, and hard-food chewing are given where the foods are simulated by foam and hard objects, and crank actuations and driving torques (an indication of muscular activities) required are compared for the chewing of different foods.

Mathematical modelling of oxygen transport-limited follicle growth

Mathematical modelling was used to investigate oxygen transport in the developing ovarian follicle. In contrast to previous findings, the results show that oxygen can reach the oocyte in large preantral follicles. This is largely due to the inclusion of fluid voidage in the model and improved estimates of oxygen diffusion coefficients through the granulosa. The results also demonstrate that preantral follicles will eventually reach a size beyond which further growth will result in the follicle becoming increasingly anoxic. The predicted size range at which this occurs is consistent with the size range at which antrum formation is observed in many mammals. This suggests that the antrum formation stage of follicular growth may be pivotal to the further development and ultimate fate of the follicle, and that antrum formation itself may represent a mechanism by which the follicle can overcome oxygen limitations. This was supported through extension of the model to the antral follicle, which showed that antrum formation can provide a way in which the follicle can continue to grow and yet avoid becoming hypoxic. The results of the model were consistent with observed follicle development.

Choosing new ways to chew: a robotic model of the human masticatory system for reproducing chewing behaviors

This paper discusses the efforts to design a robotic device that can be used to reproduce the mastication process in a mechanically controllable way while the masticatory efficiency and/or food dynamics are assessed quantitatively. While being aimed at a robotic device that is able to fully reproduce human chewing behaviors, this paper is about building and simulating its robotic model. Following an examination into the biological muscles of mastication, the muscles responsible for the chewing movements are represented by a set of linear actuators and are placed between the mandible and the skull via spherical joints, resulting in a robotic mechanism. Simulations for the mandible movements with respect to the given muscular actuations, and for the muscular actuations required for a real human chewing pattern, are conducted using the Solidworks and COSMOS/Motion.

Theoretical investigation into the dissolved oxygen levels in follicular fluid of the developing human follicle using mathematical modelling

Oxygen levels in the follicle are likely to be critical to follicle development. However, a quantitative description of oxygen levels in the follicle is lacking. Mathematical modelling was used to predict the dissolved oxygen levels in the follicular fluid of the developing human follicle. The model predictions showed that follicular fluid dissolved oxygen levels are highly variable among follicles, due to the unique geometry of individual follicles. More generally, predictions showed that oxygen levels in follicular fluid increase rapidly during the initial early antral stages of follicle growth before peaking in the later early antral phase. Follicular fluid dissolved oxygen levels then decline through to the beginning of the pre-ovulatory phase, from which they increase through to ovulation. Based on the best available parameter estimates, the model predictions suggest that the mean dissolved oxygen levels in human follicular fluid during the late antral and pre-ovulatory phases range between 11 and 51 mmHg (approximately 1.5-6.7 vol%). These predictions suggest that the human ovarian follicle is a low-oxygen environment that is often challenged by hypoxia, and are in agreement with only some published data on follicular fluid oxygen levels. Predictions are discussed in relation to follicle health and oocyte culture.

Design and Characterization of a Peristaltic Actuator Inspired by Esophageal Swallowing

The specification and design of a novel peristaltic actuator is communicated. The actuation manifests as a continuous, distributed, and compliant peristaltic actuation. The occlusive nature of force distribution on the transport conduit results in materials being transported in front of a wave which has features of geometry and wave tail seal pressure. The behavior of these aspects profoundly affects the transport process. The device, of silicone rubber construction, has no internal skeletal structure and is pneumatically actuated which allows for continuous and compliant transport. The device is characterized by the synergy of geometrical and occlusive pressure measurements in response to actuation. This is performed for the “dry swallow” case (with no bolus) for single peak, single inflection waves. Techniques typical of medical investigation were exploited. Wave geometry was captured by articulography, complemented by wave seal pressure investigation by manometry. This paper describes the inspiration, specification, and experimental techniques used to develop and characterize the behavior of the biologically inspired, peristaltic, robotic device for assertion pressures up to 71.5 kPa. It is found that the device is capable of producing wave amplitudes and seal pressures of a similar magnitude (complete occlusion with >15-kPa seal) to the human esophagus which confirms achievement of the fundamental peristaltic parameters.

Mastication Robots - Biological Inspiration to Implementation

Robotic Models of the Masticatory System.- Mastication Robot of Linear Actuation.- Mastication Robot of Crank Actuation.- Mastication Robot of a Crank-Slider Linkage.- Measurement and Reproduction of Mastication Movement.- Robotic Chewing Experiments.- Understanding Food Texture Using Masticatory Robots.- Neural Control of a Mastication Robot.- Knowledge System of Human Chewing Behaviours.