Film formation and surface properties of enzymatically crosslinked casein films

The use of renewable materials as barrier material is currently intensively investigated. Biopolymers such as polysaccharides, lipids, and proteins have been studied as barrier materials. Protein‐based films often possess good gas barrier properties, but because of their hydrophilic nature the gas barrier properties are sensitive to humidity. The improvement of the properties of sodium caseinate barrier films in potential packaging applications was studied by investigating the effects of enzymatic treatment and plasticizer on the film properties. Oxidoreductases Trametes hirsuta laccase (ThL) and Trichoderma reesei tyrosinase (TrTyr) were compared with transglutaminase for crosslinking of the sodium caseinate molecules in the films and coatings. All of the studied enzymes were able to crosslink sodium caseinate. Film solubility tests, protein electrophoresis, contact angle measurements, and atomic force microscopy studies showed that TrTyr treatment results in sodium caseinate films and coatings with better overall properties compared to treatment with ThL. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Support for solar PV deployment in Spain: Some policy lessons

This paper provides an overview of the trends of the Spanish solar PV feed-in tariff (FIT) and its design elements, identifies some implications for the effective and cost-efficient deployment of solar PV in Spain and infers some lessons which might be useful for the implementation of support for solar PV elsewhere. Our analysis is based on a throughout revision of the relevant legislation, official data on deployment and related expenditure, informal discussions with key stakeholders and written documents. Several key design elements within FITs that should be implemented and other elements that should be avoided in order to have an effective and cost-efficient promotion of solar PV are identified. All in all, the specific design elements to be included are clearly contingent upon the preferences and priorities of policymakers.     

Anisotropy of optical and mechanical properties of stretched low density polyethylene

Summary Parallel measurements of IR dichroism, birefringence and microhardness anisotropy of drawn low density polyethylene films have been carried out. The angle α between the dipole moment vector of the IR band at 1367 cm⁻¹ and the chain axis has a value of 50°. The longitudinal and transverse moduli of the drawn samples, measured by microhardness indentations, increase as the draw ratio increases after passing through a minimum for a draw ratio of around 1.5. Received: 27 April 1998/Revised version: 22 July 1998/Accepted: 22 July 1998     

Investigation of char strength and expansion properties of an intumescent coating exposed to rapid heating rates

An efficient and space saving method for passive fire protection is the use of intumescent coatings, which swell when exposed to heat, forming an insulating char layer on top of the virgin coating. Although the temperature curves related to so-called cellulosic fires are often referred to as slow heating curves, special cases where the protective char is mechanically damaged and partly removed can cause extremely fast heating of the coating. This situation, for a solvent based intumescent coating, is simulated using direct insertion of free films into a muffle oven. The char formed is evaluated with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition, char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147 μm) free coating films, a tendency to contract in the horizontal plane was observed. The experimental approach is relevant for testing of intumescent coatings used in buildings where moving or falling objects may damage the char during a fire.     

Preparation of GdBa2Cu3O6+x (GdBCO) precursor powder by spray-drying a nitrate solution containing PEG

Several precursor powders, obtained after precipitation from metal nitrate solution containing polyethylene glycol (PEG) (inside a Pyrex glass reactor or by spray-drying), and their thermal evolution to GdBa₂Cu₃O_6+x (GdBCO) were analyzed by thermogravimetry, differential thermal analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction. The amount of PEG had a crucial role in the BaCO₃ content of the “Kjeldahl precursors,” but a minor effect on the degree of transformation to GdBCO at 900°C, which did not reach completion after 1 hour. In contrast, a low-PEG spray-dried powder led to almost 100% GdBCO in only 5 minutes. The high degree of cation dispersion reached by spray-drying and the coexistence with a liquid phase can explain this short reaction time. The spray-dried powder compares favorably with the mechanical mix of metal oxides and Ba carbonate that is commonly used as precursor powder for the synthesis following a solid-state reaction.     

Multirepresentation,Multiheuristic A* search‐based motion planning for a free‐floating underwater vehicle‐manipulator system in unknown environment

A key challenge in autonomous mobile manipulation is the ability to determine, in real time, how to safely execute complex tasks when placed in unknown or changing world. Addressing this issue for Intervention Autonomous Underwater Vehicles (I‐AUVs), operating in potentially unstructured environment is becoming essential. Our research focuses on using motion planning to increase the I‐AUVs autonomy, and on addressing three major challenges: (a) producing consistent deterministic trajectories, (b) addressing the high dimensionality of the system and its impact on the real‐time response, and (c) coordinating the motion between the floating vehicle and the arm. The latter challenge is of high importance to achieve the accuracy required for manipulation, especially considering the floating nature of the AUV and the control challenges that come with it. In this study, for the first time, we demonstrate experimental results performing manipulation in unknown environment. The Multirepresentation, Multiheuristic A* (MR‐MHA*) search‐based planner, previously tested only in simulation and in a known a priori environment, is now extended to control Girona500 I‐AUV performing a Valve‐Turning intervention in a water tank. To this aim, the AUV was upgraded with an in‐house‐developed laser scanner to gather three‐dimensional (3D) point clouds for building, in real time, an occupancy grid map (octomap) of the environment. The MR‐MHA* motion planner used this octomap to plan, in real time, collision‐free trajectories. To achieve the accuracy required to complete the task, a vision‐based navigation method was employed. In addition, to reinforce the safety, accounting for the localization uncertainty, a cost function was introduced to keep minimum clearance in the planning. Moreover a visual‐servoing method had to be implemented to complete the last step of the manipulation with the desired accuracy. Lastly, we further analyzed the approach performance from both loose‐coupling and clearance perspectives. Our results show the success and efficiency of the approach to meet the desired behavior, as well as the ability to adapt to unknown environments.     

Blocking versus robustness in industrial contexts

The paper discusses the similarities and differences between blocking factors (blocked designs) and noise factors (robust designs) in industrial two‐level factorial experiments. The discussion covers from the objectives of both design types and the nature of blocking and noise factors to the types of designs and the assumptions needed in each case. The conclusions are as follows: the nature and characteristics of noise and blocking factors are equal or very similar; the designs used in both situations are also similar; and the main differences lie in the assumptions and the objectives. The paper argues that the objectives are not in conflict and can easily be harmonized. In consequence, we argue in favor of a unified approach that would clarify the issue, especially for students and practitioners.