Rheological and structural properties of gels cross-linked with fungal laccases

Arabinoxylans (AXs) and sugar beet fibre (Fibrex) are substances which have the potential of forming cross-linked hard gels. AXs, which are classified as hemicelluloses, are the major non-starch polysaccharides in wheat bran. Sugar beet pectin is the main soluble fibre in Fibrex. The cross-linking potential of AX and Fibrex refers to the ferulic acid units, which are ester linked to the molecules´ main chain. The more ferulic acid moieties are present on the polysaccharide backbone, the more covalent cross-links may be generated. A modified AX extraction method, in which the incubation time and concentration of alkaline extracts were optimised, has been applied to extract AX from wheat bran. In addition, a modified hydrothermal extraction method has been used to extract Fibrex. The extractable AXs from wheat bran were cross-linked by the commercial laccase C (LccC) and self-produced laccases from Funalia trogii (LccFtr) and Pleurotus pulmonarius (LccPpu). Dynamic oscillation measurements on AX gels presented mechanical spectra, including storage modulus, loss modulus and loss factor of the gels. Gel samples demonstrated viscoelastic properties, which remained constant for four weeks in the gels formed with LccFtr and LccPpu. Arabinoxylan gel characteristics, including high water holding capacity, swelling ratio in saliva, and heat resistance indicated a covalently cross-linked network. Mediators (caffeic acid and ABTS) and citrus pectin did not enhance the elastic properties of the gels. Fibrex was successfully cross-linked with LccFtr to an edible gel. Analysing rheological and structural characteristics of the Fibrex gels including high water holding capacity, swelling ratio in saliva, and heat resistance) showed the viscoelastic behaviour of the gels which was attributed to the covalently cross-linked network. However, vanillin, as a mediator, and citrus pectin did not enhance covalent cross-links and elastic properties of the Fibrex gels. Rheological properties and storage stability of sweetened Fibrex gels indicated a constant storage modulus during four weeks storage. Rheological behaviour and structural properties of the Fibrex gels and AX gels were compared with gelatin gels as a reference. Using laccases as an oxidant provided gels with a solid and stable texture, comparable in firmness to traditional gelatin gels. Cross-linked gels may find uses in pharmaceutical and other industrial applications, which require a heat resistant gel that forms easily at room temperature. They also represent an ethical alternative for manufacturing vegan, halal, and kosher food

A Real-time Signal Control System to Minimize Emissions at Isolated Intersections

Continuous transportation demand growth in recent years has led to many traffic issues in urban areas. Among the most challenging ones are traffic congestion and the associated vehicular emissions. Efficient design of traffic signal control systems can be a promising approach to address these problems. This research develops a real-time signal control system, which optimizes signal timings at an under-saturated isolated intersection by minimizing total vehicular emissions. A combination of previously introduced analytical models based on traffic flow theory has been used. These models are able to estimate time spent per driving mode (i.e., time spent accelerating, decelerating, cruising, and idling) as a function of demand, vehicle arrival times, saturation flow, and signal control parameters. Information on vehicle activity is used along with the Vehicle Specific Power (VSP) model, which estimates emission rates per time spent in each operating mode to obtain total emissions per cycle. For the evaluation of the proposed method, data from two real-world intersections of Mesogion and Katechaki Avenues located in Athens, Greece and University and San Pablo Avenues, in Berkeley, CA has been used. The evaluation has been performed through both deterministic (i.e. under the assumption of perfect information for all inputs) and stochastic (i.e. without having perfect information for some inputs) arrival tests. The results of evaluation tests have shown that the proposed emission-based signal control system reduces emissions compared to traditional vehicle-based signal control system in most cases

Intersection Signal Control and Design for Improved Person Mobility and Air Quality in Urban Multimodal Transportation Systems

Alternative geometric designs (e.g. roundabouts) and multi-objective signal control strategies are promising measures to improve sustainability of traffic networks. However, roundabouts are mostly used because of their safety and operational advantages. There has been less attention to the environmental performance of roundabouts. Also, the existing studies have been mostly used through field measurements and current simulation models, which need high calibration efforts and they are not inclusive in terms of considering all influencing factors on vehicular emissions at roundabouts. Furthermore, the existing real-time signal control strategies do not account for the emission rates of different vehicle types (e.g. cars and buses). In addition, the real-time multi-objective signal control systems does not consider environmental objectives. This dissertation develops a real-time bi-objective signal control system for isolated intersections, which operate at undersaturated traffic conditions that minimizes a weighted combination of vehicle delay (or person delay) and emissions of auto and transit vehicles. Pareto Frontiers of the optimal solutions are presented to help decision makers select the most appropriate combinations of objectives to achieve desirable levels of delay and emissions. Additionally, a simple simulation tool based on Cellular Automata (CA) model of traffic simulation is developed to estimate delay and reproduce vehicle trajectories for emission estimation. The models are used to compare the operational and environmental performance of roundabouts and signalized intersections and perform sensitivity analysis with respect to total traffic demand, left turn ratio, and pedestrian volume. Evaluation tests show that replacing a signalized intersection with a roundabout results in improved delay and emissions at undersaturated traffic conditions and any pedestrian volume. It also shows that roundabouts’ performance is less affected by high left turning demand compared to signalized intersections. On the contrary, roundabouts’ performance is sensitive to frequent pedestrian crossings while the performance of signalized intersections is not affected by pedestrian crossings

Don't cancel the surgery just yet! A case report of positive preoperative pregnancy test due to a soft tissue sarcoma production of ectopic beta human chorionic gonadotropin.

Soft tissue sarcomas are a rare group of mesenchymal malignancies which can range from low to high grade. These tumors have different clinical, radiographic, and histopathological characteristics. Beta human chorionic gonadotropin is a naturally secreted hormone by placental syncytiotrophoblast cells during pregnancy. On very rare occasions, sarcomas can develop the ability to ectopically produce human chorionic gonadotropin. Very few cases exist in the literature of soft tissue sarcomas expressing this hormone. We report the case of a 55-year-old female who presented with a posterior thigh soft tissue sarcoma who on the day of surgical resection was found to have an unusually elevated serum human chorionic gonadotropin. Positive immunohistochemical staining of the resected mass confirmed the sarcoma as the source of the beta human chorionic gonadotropin

The mitral valve computational anatomy and geometry analysis

We present a novel methodology to characterize and quantify the Mitral Valve (MV) geometry and physical attributes in a multi-resolution framework. A multi-scale decomposition was implemented to model the MV geometry by using superquadric shape primitives and spectral reconstruction of the finer-scale geometric details. Superquadrics provide a basis to normalize the size and approximate a basic model of the MV geometry. The point-wise difference between the original geometry and the superquadric model denotes the finer-scale geometric details, which can be modeled as a scalar attribute for the MV model development. The additive decomposition of the basic MV geometry from geometric details (attributes) allows recovering the actual geometry by superposition of the superquadric approximation and the finer-details model. We implemented a lasso optimization algorithm to perform spectral analysis and develop the Fourier reconstruction of the geometric details. The spectral modeling enabled us to resample the geometric details or use spectral filters in order to adjust the spatial resolution in the model reconstruction. It also provides the basis to control the level of detail in the final model reconstruction by applying low-pass filters in the frequency domain. The higher-order attributes such as internal fiber architecture can be integrated with the geometric models using the same framework. We applied our pipeline to create models of three ovine MVs based on computed-tomography 3D images with micrometer resolution. We were able to quantify the MV leaflet geometry, reconstruct models with custom level of geometric details, and develop medial representation of the MV leaflet structure. The results show that our methodology for geometry analysis provides a basis for assessing patient-specific geometries and facilitates developing population-averaged models. Ultimately, this approach allows building personalized image-based computational models for medical device design and surgical treatment simulations.Mechanical Engineerin

Contrasting space-time schemes for MIMO FSO systems with non-coherent modulation

International audienc

Fractional Dynamics of Network Growth Constrained by aging Node Interactions

In many social complex systems, in which agents are linked by non-linear interactions, the history of events strongly influences the whole network dynamics. However, a class of "commonly accepted beliefs" seems rarely studied. In this paper, we examine how the growth process of a (social) network is influenced by past circumstances. In order to tackle this cause, we simply modify the well known preferential attachment mechanism by imposing a time dependent kernel function in the network evolution equation. This approach leads to a fractional order Barabasi-Albert (BA) differential equation, generalizing the BA model. Our results show that, with passing time, an aging process is observed for the network dynamics. The aging process leads to a decay for the node degree values, thereby creating an opposing process to the preferential attachment mechanism. On one hand, based on the preferential attachment mechanism, nodes with a high degree are more likely to absorb links; but, on the other hand, a node's age has a reduced chance for new connections. This competitive scenario allows an increased chance for younger members to become a hub. Simulations of such a network growth with aging constraint confirm the results found from solving the fractional BA equation. We also report, as an exemplary application, an investigation of the collaboration network between Hollywood movie actors. It is undubiously shown that a decay in the dynamics of their collaboration rate is found, - even including a sex difference. Such findings suggest a widely universal application of the so generalized BA model.Comment: 13 pages; 5 figures; 71 references; as prepared for submission to PLOS ON

Impact of Link Parameters and Channel Correlation on the Performance of FSO Systems With the Differential Signaling Technique

We investigate the effects of link parameters and the channel correlation coefficient on the detection threshold, Q-factor, and bit-error-rate (BER) of a free-space optical system employing a differential signaling scheme. In systems employing differential signaling schemes, the mean value of the signal is used as the detection threshold level, provided that differential links are identical or highly correlated. However, in reality, the underlying links are not essentially identical and have a low level of correlation. To show the significance of the link parameters as well as the correlation coefficient, we derive analytical relations describing the effect of weak turbulence and we determine the improvement of Q-factor with the channel correlation. Further, for the same signal-to-noise ratio, we demonstrate that a link with a higher extinction ratio offers improved performance. We also propose a closed-form expression of the system BER. We present experimental results showing improved Q-factor for the correlated channel case compared to the uncorrelated channel

Optical wireless communication systems

The emerging field of optical wireless communication (OWC) systems is seen as potential complementary technology to the radio frequency wireless communications in certain applications. It is deemed as a possible technology in the future 5th Generation communication networks to address the spectrum congestion and improve the system's capacity. More research and developments in OWC is still needed in order for it to be adopted in current and future communication systems. This special issue brings together research papers on OWC covering free space optic, visible communications and ultraviolet communications

EFFECTS OF LAND USE CHANGE ON SURFACE WATER REGIME (CASE STUDY ORUMIEH LAKE OF IRAN)

AbstractLand use change from rangeland and forest to agriculture and orchard areas which affected water regime, are widely occurred in many parts of Iran. The above mentioned problem has happened in Orumieh Lake basin for an area of 1146 km2 which is located in northwest of Iran. The recent land use map was resulted through satellite images of 1990, 1998 and 2006 as well as field observations and the previous period map was performed by using the aerial photographs of 1955 (which is considered as the oldest documents). In this period 14% of rangeland is changed into dry farming and 7% of irrigated farming is converted to orchard. The results show that due to land use change in this area, the mean annual discharge has not changed but maximum daily discharge increased and minimum daily discharge reduced