Biodegradation of poly(vinylalcohol-co-ethylene) with the fungus phanerochaete chrysosporium

Under appropriate conditions for lignine peroxidase production in a culture medium that contains spores of Phanerochaete Chrysosporium fungus, the biodegradation of ethylene vinyl alcohol (EVOH) pellets with 27% mole of ethylene content was observed after 30 days. The oxidative degradation was detected by Fourier Transform Infrared Spectroscopy (FTIR) through the formation of hydroperoxides containing chains which were broken with degradation time. Differential Scanning Calorimetry (DSC) initially showed only one melting peak and after 30 days two peaks appeared on the thermogram, one due to the remaining copolymer that did not change with degradation time and the other due to the polymer degradation sequence. When EVOH film with a similar amount of ethylene was used, the initial melting temperature (T_m) decreased during degradation and a second crystalline sequence with a lower T_m was produced, indicating that both copolymer sequences were degraded. Observed differences in the biodegradative behavior between EVOH pellets and EVOH film were mainly due to the changes in crystallinity of the copolymer induced by film processing. The initial EVOH film showed a lower crystallinity and the presence of double bonds, which favors the degradative process. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

Unity for all

It is quite paradoxical that, in spite of the strong energy dimension of the first European Union treaties and of the relevance of energy for the European economy, until very recently it has been difficult to identify a common European energy policy. Several factors make defining a common European energy policy particularly difficult. There is a conflict between economic efficiency, which has led to the creation of common European gas and electricity markets, and national sovereignty, which makes member states reluctant to leave their supply security in others' hands. Another conflict is the one arising because of policies favoring the so-called "national champions." It is difficult to reach a consensus on these highly political issues. Nuclear energy is yet another problem. Until recently, most of the measures adopted at the European level have lacked an integral vision: usually policies have focused on a particular aspect, fuel, or technology, ignoring the rest. The outcome has been an unbalanced, nonharmonized development of different energy aspects that harms effectiveness and perdurability.     

Riparian Forest Harvesting Effects on Maximum Water Temperatures in Wetland-sourced Headwater Streams from the Nicola River Watershed, British Columbia, Canada

Water temperature was continuously recorded during the ice-free season between June/July and October/November at 90 sites with lentic and lotic stream sources distributed throughout the Nicola River watershed (British Columbia, Canada) in 1999, 2000, and 2001. The eight lentic-sourced stream temperature monitoring sites were located in two adjacent watersheds. The headwaters and riparian areas around the wetland outlet of the treatment watershed were harvested during the overwinter period between 1999 and 2000. Areas around and downstream of the headwater wetland outlet in the control watershed were not harvested. Reducing riparian shade by harvesting activities increased maximum stream temperatures in the treatment watershed by up to 1–2°C relative to the control watershed. Because of the general downstream cooling trends in lentic-sourced headwater streams, riparian harvesting activities in these regions have a reduced thermal impact relative to similar harvesting alongside lotic-sourced headwater streams, whose maximum stream temperatures may warm by up to 8°C following harvesting. The downstream influence of elevated maximum stream temperatures from riparian harvesting of lentic-sourced headwater streams appears to be localized, but persists for at least 2 years following harvesting. Both lentic-sourced treatment and control streams in the current study relaxed towards baseline equilibrium temperature estimated by the lotic-sourced watershed trend within several hundred meters of downstream travel distance, with cooling rates proportional to the distance from expected thermal equilibrium. Due to the heating in wetland-sourced stream reaches adjacent to riparian harvesting, the regions downstream of treatment areas cool more rapidly than similar regions in control watersheds as the stream attempts to achieve thermal equilibrium.     

Miniature microstrip bandpass filter with large stopbands

A careful analysis of a classical filter configuration with large stopbands is made. An understanding of the structure behaviour is gained that allows design on safe grounds. A 1.3 GHz microstrip prototype using parallel-coupled-lines inverters is presented. Design equations for this type of inverter are also given.     

Map Generation by Cooperative Low-Cost Robots in Structured Unknown Environments

In this paper we present some results obtained with a troupe of low-cost robots designed to cooperatively explore unknown structured orthogonal environments. In order to improve the covering of the explored zone the robots show different behaviours (routine, normal and anxious) and cooperate by transferring each other the perceived environment when they meet; therefore, not all the information of the non-returning robots is lost provided that they had encountered robots that safely returned. The returning robots deliver to a host their perceived and communicated (by other robots) partial maps and the host incrementally generates the most plausible map of the environment. To perform the map generation, a fusion, completion and alignment process of the partial maps, based on fuzzy techniques, has been developed.     

Preliminary assessment of the safety and immunogenicity of a new CTXPhi-negative, hemagglutinin/protease-defective El Tor strain as a cholera vaccine candidate

Vibrio cholerae 638 (El Tor, Ogawa), a new CTXPhi-negative hemagglutinin/protease-defective strain that is a cholera vaccine candidate, was examined for safety and immunogenicity in healthy adult volunteers. In a double-blind placebo-controlled study, no significant adverse reactions were observed in volunteers ingesting strain 638. Four volunteers of 42 who ingested strain 638 and 1 of 14 who received placebo experienced loose stools. The strain strongly colonized the human small bowel, as evidenced by its isolation from the stools of 37 of 42 volunteers. V. cholerae 638, at doses ranging from 4 x 10(7) to 2 x 10(9) vibrios, elicited significant serum vibriocidal antibody and anti-Ogawa immunoglobulin A antibody secreting cell responses.     

Atomic Layer Deposition for Membranes,Metamaterials, and Mechanisms

Bending and folding techniques such as origami and kirigami enable the scale‐invariant design of 3D structures, metamaterials, and robots from 2D starting materials. These design principles are especially valuable for small systems because most micro‐ and nanofabrication involves lithographic patterning of planar materials. Ultrathin films of inorganic materials serve as an ideal substrate for the fabrication of flexible microsystems because they possess high intrinsic strength, are not susceptible to plasticity, and are easily integrated into microfabrication processes. Here, atomic layer deposition (ALD) is employed to synthesize films down to 2 nm thickness to create membranes, metamaterials, and machines with micrometer‐scale dimensions. Two materials are studied as model systems: ultrathin SiO₂ and Pt. In this thickness limit, ALD films of these materials behave elastically and can be fabricated with fJ‐scale bending stiffnesses. Further, ALD membranes are utilized to design micrometer‐scale mechanical metamaterials and magnetically actuated 3D devices. These results establish thin ALD films as a scalable basis for micrometer‐scale actuators and robotics.     

Authentication in mobile devices through hand gesture recognition

This article proposes an innovative biometric technique based on the idea of authenticating a person on a mobile device by gesture recognition. To accomplish this aim, a user is prompted to be recognized by a gesture he/she performs moving his/her hand while holding a mobile device with an accelerometer embedded. As users are not able to repeat a gesture exactly in the air, an algorithm based on sequence alignment is developed to correct slight differences between repetitions of the same gesture. The robustness of this biometric technique has been studied within 2 different tests analyzing a database of 100 users with real falsifications. Equal Error Rates of 2.01 and 4.82% have been obtained in a zero-effort and an active impostor attack, respectively. A permanence evaluation is also presented from the analysis of the repetition of the gestures of 25 users in 10 sessions over a month. Furthermore, two different gesture databases have been developed: one made up of 100 genuine identifying 3-D hand gestures and 3 impostors trying to falsify each of them and another with 25 volunteers repeating their identifying 3-D hand gesture in 10 sessions over a month. These databases are the most extensive in published studies, to the best of our knowledge.     

Loop-closing: A typicality approach

Loop-closing has long been identified as a critical issue when building maps from local observations. Topological mapping methods abstract the problem of how loops are closed from the problem of how to determine the metrical layout of places in the map and how to deal with noisy sensors.The typicality problem refers to the identification of new classes in a general classification context. This typicality concept is used in this paper to help a robot acquire a topological representation of the environment during its exploration phase. The problem is addressed using the INCA statistic which follows a distance-based approach.In this paper we describe a place recognition approach based on match testing by means of the INCA test. We describe the theoretical basis of the approach and present extensive experimental results performed in both a simulated and a real robot-environment system; Behaviour Based philosophy is used to construct the whole control architecture. Obtained results show the validity of the approach.     

Intensified iterative deepening A* with application to job shop scheduling

We propose a novel, exact any-time search strategy that combines iterative deepening \(\text{ A}\) * ( \(\text{ IDA}\) *) with depth-first search and we consider the job shop scheduling problem with makespan minimization as a test bed. The combination of these search strategies is done so that limited depth-first searches are issued from some of the states distributed along the frontier reached by \(\text{ IDA}\) * in each iteration. In this way, a proper equilibrium between intensification and diversification search effort is achieved while the algorithm keeps the capability of obtaining tight lower bounds. To evaluate the proposed strategy and to compare it with other methods, we have conducted an experimental study involving a number of conventional benchmarks with instances of various sizes. The results of these experiments show that the proposed algorithm takes less time than other methods in reaching optimal solutions for small and medium-size instances, and that it is quite competitive in reaching good solutions and good lower bounds for the instances that cannot be optimally solved.