Synthesis and characterization of poly (styrene‐b‐[(butadiene)1−x‐(ethylene‐co‐butylene)x] ‐b‐styrene) star‐like molecular polymers produced by partial hydrogenation of SBS

This article reports the synthesis and characterization of four arm star‐shaped poly(styrene‐b‐[(butadiene)_1?x‐(ethylene‐co‐butylene)_x]‐b‐styrene) (SBEBS) copolymers. A series of SBEBS copolymers with different compositions of the elastomeric block were produced by hydrogenating a given poly(styrene‐b‐butadiene‐b‐styrene) (SBS) copolymer using a catalyst prepared from bis(η⁵‐cyclopentadienyl)titanium(IV) dichloride and n‐butyllithium. The characterization was accomplished by proton nuclear magnetic resonance spectroscopy (¹H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicate that there is a selective saturation of the polybutadiene block over the polystyrene block; this selectivity was determined by the Ti/Li molar ratio and the concentration of Ti. It was observed that the saturation rate of the 1,2‐vinyl was higher than that of the 1,4‐trans and 1,4‐cis poly(butadiene)‐b isomers. The DSC and DMA results indicate that the degree of hydrogenation had a profound effect on the polymer's relaxation behavior. All samples exhibited a biphasic system behavior with two distinct transitions corresponding to the elastomeric and polystyrene blocks. SBEBS copolymers with higher saturation levels (>33%) exhibited a crystalline character. The TGA results indicated a characteristic weight loss temperature in all samples, with slightly higher thermal degradation stabilities in the materials with higher degrees of saturation. POLYM. ENG. SCI., 54:2332–2344, 2014. © 2013 Society of Plastics Engineers     

Software tools for HVAC research

Energy saving methods can be employed to reduce energy consumption in buildings, or improve indoor thermal conditions. An example of those methods is the use of permeable coverings, but there are other important parameters like thermal inertia. To understand and predict these energy saving procedures, one may employ different software resources. In the present paper a review of existing software resources is carried out, and, as a consequence of this review, HAM tools were selected to simulate the indoor environment of school buildings. Results show that parameters like thermal inertia can interfere in the solar heat gains, changing the building time constant. Other parameters, like air changes per hour or the use of permeable coverings, present a clear enhancement of indoor environment conditions.     

Controlled release matrices and micro/nanoparticles of chitosan with antimicrobial potential: development of new strategies for microbial control in agriculture

The control of micro‐organisms responsible for pre‐ and postharvest diseases of agricultural products, mainly viruses and fungi, is a problem that remains unresolved, together with the environmental impact of the excessive use of chemicals to tackle this problem. Current efforts are focused on the search for efficient alternatives for microbial control that will not result in damage to the environment or an imbalance in the existing biota. One alternative is the use of natural antimicrobial compounds such as chitosan, a linear cationic biopolymer, which is biodegradable, biocompatible and non‐toxic, has filmogenic properties and is capable of forming matrices for the transport of active substances. The study of chitosan has attracted great interest owing to its ability to form complexes or matrices for the controlled release of active compounds such as micro‐ and nanoparticles, which, together with the biological properties of chitosan, has allowed a major breakthrough in the pharmaceutical and biomedical industries. Another important field of study is the development of chitosan‐based matrices for the controlled release of active compounds in areas such as agriculture and food for the control of viruses, bacteria and fungi, which is one of the least exploited areas and holds much promise for future research. © 2013 Society of Chemical Industry     

An efficient omnidirectional vision system for soccer robots: From calibration to object detection

Robotic soccer is nowadays a popular research domain in the area of multi-robot systems. In the context of RoboCup, the Middle Size League is one of the most challenging. This paper presents an efficient omnidirectional vision system for real-time object detection, developed for the robotic soccer team of the University of Aveiro, CAMBADA. The vision system is used to find the ball and white lines, which are used for self-localization, as well as to find the presence of obstacles. Algorithms for detecting these objects and also for calibrating most of the parameters of the vision system are presented in this paper. We also propose an efficient approach for detecting arbitrary FIFA balls, which is an important topic of research in the Middle Size League. The experimental results that we present show the effectiveness of our algorithms, both in terms of accuracy and processing time, as well as the results that the team has been achieving: 1st place in RoboCup 2008, 3rd place in 2009 and 1st place in the mandatory technical challenge in RoboCup 2009, where the robots have to play with an arbitrary standard FIFA ball.     

Biological Removal of High Loads of Thiosulfate Using a Trickling Filter Under Alkaline Conditions

Uncontrolled release of thiosulfate can cause high oxygen demand, or generate toxic compounds under anaerobic scenarios. Biooxidation of thiosulfate in a biotrickling filter (BTF) colonized by an alkaliphilic sulfide-oxidizing bacterial consortium was studied at pH ≈10. Inlet thiosulfate concentrations were varied from 3.5 to 21.3 g L^?1, with a residence time of 216 s, emulating conditions encountered in wastewater from mining processes. Sulfate production, oxygen concentration, and biomass in both packing and effluent were periodically analyzed to characterize bioreactor performance. Removal efficiencies near 100 % were obtained during the entire experimental period, with a maximum elimination capacity of 242 g thiosulfate m^?3 h^?1. Although the BTF was able to transfer large amounts of oxygen to biooxidize thiosulfate to sulfate, under high initial thiosulfate loads, thiosulfate was not completely oxidized to sulfate, since biooxidation was conditioned to oxygen supply. Respirometric tests performed to investigate biomass adaptation and activity revealed oxygen consumption values of 0.5 mmol O₂ (g protein)^?1 min^?1 for the period with the highest thiosulfate inlet load.     

TETRA radio performance evaluated via the software package TETRASIM

TETRA (TErrestrial Trunked RAdio) is a digital mobile radio standard for voice and data transmission. It aims at satisfying the growing request of applications and facilities coming from professional users and emergency services. The system has been standardized by ETSI (European Telecommunications Standards Institute) and is provided with an European harmonized frequency band. The first TETRA networks appeared on the market in 1997. This paper reports TETRA radio performance evaluated via a simulation software package, named TETRASIM, entirely developed at CSELT according to TETRA specifications. The simulation results have been obtained for some of the traffic and control channels specified by the standard, in terms of BER (Bit Error Rate) and MER (Message Erasure Rate). As far as the simulated receiver scheme is concerned, the characteristics of the equivalent low-pass filters and the adopted synchronization technique are reported. The simulated demodulator uses a differential detection scheme with soft decision outputs in the case of coded channels. Performance analyses and results comparison are provided by taking into account the effects of signal-to-noise ratio, co-channel interference, adjacent channel interference, propagation models defined in the standard and mobile unit speed. The simulation results reported in this work have been included in the ETR (ETSI Technical Report) “TETRA Designers’ Guide Part 2: Radio and Traffic Performance”. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biochemical mechanism of the effect of barbital on rifamycin B biosynthesis by Amycolatopsis mediterranei (M18 strain)

It is well known that 5,5-diethylbarbituric acid (barbital) in the culture medium can stimulate the production of rifamycin B by Amycolatopsis mediterranei, particularly in industrial processes. However, the mechanism by which barbital exerts this effect is unknown. Results in this work show that the barbital effect is only evident under low aeration conditions (50-ml microfermentors with 7 ml of medium, 0.08 l/h air flow). Under these conditions, cultures with barbital showed similar CO2 production (in relation to a control without barbital), but higher oxygen uptake indicated that the extra O2 consumed was used in the increased rifamycin biosynthesis. Moreover, using a resting cell system where no antibiotic is produced, it was possible to show that barbital inhibits the respiratory chain, since O2 uptake decreased by 30%. Finally, we present biochemical results that suggest that a cytochrome P450-type monoxygenase, which can use atmospheric oxygen, is induced by barbital in an industrial-type strain of A. mediterranei.     

Raman lidar monitoring of extinction and backscattering of African dust layers and dust characterization

Results on the monitoring of strong African dust outbreaks at Lecce in the southeastern corner of Italy (40 degrees 20' N, 18 degrees 6' E) during May 2001 are presented. This activity has been performed in the framework of the European Aerosol Research Lidar Network (EARLINET). The lidar station of Lecce is located on a flat rural area that is approximately 800 km from the northern Africa coast. So it is closer to Africa than most of all other EARLINET stations and allow monitoring African dust transport early in its life cycle, at all levels in the plume. An elastic-backscatter Raman lidar based on a XeF excimer laser (351 nm) has been used to monitor the time evolution and vertical structure of the dust layers and get independent measurements of the aerosol extinction and backscatter coefficients. The findings are presented in terms of vertical profiles of the extinction and backscatter coefficients and of the lidar ratio. A quite deep dust layer extending between 2 and 6 km and characterized by a backscatter coefficient of approximately 0.0016 (km sr)(-1), a lidar ratio of approximately 50 sr, and an aerosol optical depth of 0.26 was observed on 17 May 2001 between 18:55 and 20:07 UT. The layer persisted for approximately five days. Dust layers of lower optical thickness and shorter persistence time have generally been monitored at the lidar site during African dust outbreaks. Results on the chemical and morphological characterization of the dust collected at the lidar station are also given to further support the origin of the monitored aerosol layers.     

Melting and crystallization of UHMWPE skived film

Commercial skived film from ultra-high molecular-weight polyethylene (UHMWPE) with considerable uniaxial orientation of lamellae is studied by ultra-small-angle X-ray scattering (USAXS) and wide-angle X-ray scattering (WAXS) during melting and crystallization in order to identify its mechanisms of crystallization. For the analysis of the nanostructure two-dimensional USAXS patterns are analyzed by means of the multidimensional chord distribution function (CDF) method. WAXS shows that crystallization is always isotropic and fast. WAXS reflections are observed before—under certain processing conditions—the SAXS pattern becomes anisotropic. Thus crystallization is decoupled from a slower process of oriented nanostructure formation (nanoforming). If nanoforming is performed isothermally at 105 °C, the evolving nanodomain layers obtain some preferential orientation, as long as the orientation of the melt has not previously been erased by melt-annealing at temperatures of 140 °C or above. Crystallization at temperatures ≥110 °C followed by quenching leads to isotropic nanostructure. Although crystallization is always observed early in the WAXS patterns, the USAXS patterns exhibit only weak discrete scattering during isothermal treatment at temperatures of 110 °C and higher. At 105 °C anisotropic isothermal nanoforming starts after 1.5 min. The melting of the original material resembles an inverted random car-parking mechanism. Only next-neighbor correlations are observed among the crystalline layers. The average nanodomain layer thickness is only slightly increasing (26–30 nm), whereas the long period increase is strong (from 60 nm to 140 nm).