Electrically Activated Paper Actuators

This paper describes the design and fabrication of electrically controlled paper actuators that operate based on the dimensional changes that occur in paper when the moisture absorbed on the surface of the cellulose fibers changes. These actuators are called “Hygroexpansive Electrothermal Paper Actuators” (HEPAs). The actuators are made from paper, conducting polymer, and adhesive tape. They are lightweight, inexpensive, and can be fabricated using simple printing techniques. The central element of the HEPAs is a porous conducting path (used to provide electrothermal heating) that changes the moisture content of the paper and causes actuation. This conducting path is made by embedding a conducting polymer (PEDOT:PSS) within the paper, and thus making a paper/polymer composite that retains the porosity and hydrophilicity of paper. Different types of HEPAs (straight, precurved, and creased) achieved different types of motions (e.g., bending motion, accordion type motion). A theoretical model for their behavior is proposed. These actuators have been used for the manipulation of liquids and for the fabrication of an optical shutter.     

Inside Vertical-Cavity Surface-Emitting Lasers: Extracting the Refractive Index From Spatial-Spectral Mode Images

We present a method to extract the internal effective refractive index of a vertical-cavity surface-emitting laser (VCSEL) from its transverse mode images. High spatial and spectral resolution mode images of an oxide-guided VCSEL were obtained using an etalon filter and an imaging spectrometer. The refractive index and the oxide radius were extracted from the field intensity distribution and the spectral wavelength of the laser modes. The procedure was repeated at two different currents and both gave a refractive index step of 0.046 plusmn 0.006 with a 14.1-mum oxide diameter. With several degrees of freedom for error available in the refractive index extraction, this method may be extended to ion-implanted, photonic crystal, and noncircular devices     

Organic Single Crystal Patterning Method for Micrometric Photosensors

Light detection technologies are of interest due to their applications in energy conversion and optical communications. Single-crystal organic semiconductors, such as rubrene, present high detectivities and charge carrier mobility, making them attractive for light-sensing applications. Growth of high crystallinity organic crystals is achieved using vapor processes, forming crystals of arbitrary shapes and orientations and requiring posterior patterning processes. However, patterning the organic semiconductors using industry-standard microfabrication techniques is not straightforward, as these often cause irreversible damage to the crystals. Here the fabrication of patterned micrometric rubrene photosensors is demonstrated through a combination of photolithography and Reactive Ion Etching steps. Protective layers during microfabrication minimize degradation of optoelectronic properties of the organic single crystals during fabrication. Crystals undergoing the patterning process presented a survival rate of 39%. Photoresponse values of up to 41 mA W⁻¹ are obtained under illumination at 500 nm. This opens a route for the industrial-scale fabrication process of high-performance optoelectronic devices based on organic crystals semiconductors.     

On the Use of Asymmetric Windows for Robust Speech Recognition

This paper deals with the problem of searching for a suitable window for robust speech recognition in noisy conditions. A set of asymmetric windows, so-called DDR _c,w , are proposed which are controlled by two parameters, center c and width w. These windows are derived from the DDR window used in the higher-lag autocorrelation spectrum estimation (HASE) method and act over the OSA (One-Sided Autocorrelation) in order to perform spectral estimation. The two parameters, c and w, allow us to control the level of weight given to the first noisy autocorrelation coefficients and to emphasize the important ones. Finally, it is shown that the best window of the proposed set is the DDR _62,200. This window is centered around the average pitch of human speech and it provides a higher speech recognition performance over the Aurora-2 and Aurora-3 databases than those obtained by previously proposed windows.     

A multimode CMOS PA with a single propagation path

Analog Integrated Circuits and Signal Processing - In this paper a four mode 130 nm RF CMOS power amplifier (PA) in a single propagation path topology is presented and evaluated with IEEE...     

New Drug‐Structure‐Directing Agent Concept: Inherent Pharmacological Activity Combined with Templating Solid and Hollow‐Shell Mesostructured Silica Nanoparticles

One of the major challenges in medicine is the delivery and control of drug release over time. Current approaches take advantage of mesostructured silica nanoparticles (MSNs) as carriers but suffer several problems including complex synthesis that requires sequential steps for (1) removal of surfactants and (2) functionalization of MSNs to allow upload of the drugs. Here, a novel solution is presented to these restrictions: the design of drug‐structure‐directing agents (DSDAs) with dual inherent pharmacological activity and ability to direct the formation of solid and hollow‐shell MSNs. Pharmacologically active DSDAs obtained by amidation of drugs with fatty acids are allowed to form micelles, around which the inorganic species self‐assembled to form MSNs. Since the DSDAs direct the formation of MSNs, the steps to remove surfactants, functionalization, and drug upload are not required. The MSNs thus prepared provide sustained release of the drug over more than six months, as well as rapid cellular internalization by both physiological and tumoral human colon cells without affecting cell viability. Moreover, the gradual intracellular release of both, the active drug and lipid moiety with potential nutraceutical properties is proved. MSN particles designed with this approach are promising vehicles for controlled and sustained intra‐or extracellular drug‐delivery.     

Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials

Carbon fiber-reinforced polymers, used in primary structures for aircraft due to an excellent strength-to-weight ratio when compared with conventional aluminium alloy counterparts, may nowadays be considered as mature structural materials. Their use has been extended in recent decades, with several aircraft manufacturers delivering fuselages entirely manufactured with carbon composites and using advanced processing technologies. However, one of the main drawbacks of using such composites entails their poor electrical conductivity when compared with aluminium alloy competitors that leads to lightning strikes being considered a significant threat during the service life of the aircraft. Traditionally, this problem was overcome with the use of a protective copper/bronze mesh that added additional weight and reduced the effectiveness of use of the material. Moreover, this traditional sizing method is based on vast experimental campaigns carried out by subjecting composite panels to simulated lightning strike events. While this method has proven its validity, and is necessary for certification of the structure, it may be optimized with the aid provided by physically based numerical models. This paper presents a model based on the finite element method that includes the sources of damage observed in a lightning strike, such as thermal damage caused by Joule overheating and electromagnetic/acoustic pressures induced by the arc around the attachment points. The results of the model are compared with lightning strike experiments carried out in a carbon woven composite.     

Contested landscapes: territorial conflicts and the production of different ruralities in Brazil

ABSTRACT

From the perspective of Brazilian agrarian geography, the conflicts generated by land tenure disputes have as protagonists the families of the Landless Workers’ Movement (Movimento dos Trabalhadores Rurais Sem Terra), traditional landowners, and agribusiness corporations. In this article, we present a reflection on land conflicts and the spatial and territorial production of latifundia, peasant smallholders, and large-scale agribusiness through studies of the landscapes of two municipalities in the state of São Paulo. Among the various tools for analysing territorial disputes, Google Earth can be used for local, regional, and international comparative studies of how landscapes have been transformed. Informed by traditional research, the article analyses a diversity of photographs, from satellite to field shots, as evidence of landscapes that express conflicting social relations in disputes over different models of social and territorial development.     

Developing English domestic occupancy profiles

ABSTRACT

Occupancy patterns are necessary to estimate energy demand and evaluate thermal comfort in households. Because of this, many European countries are developing representative domestic schedules to replace outdated criteria. This paper evaluates the state of knowledge of UK domestic occupancy patterns and develops new domestic occupancy profiles for England. The presented research (1) characterizes methods for collecting occupancy data and inferring patterns; (2) identifies and assesses the quality of categories of occupancy patterns used in building simulation; and (3) develops updated occupancy profiles. A systematic scoping review identified social and monitoring surveys as the most deployed data-collection methods. A systematic literature review also established that the occupancy categories most frequently used in UK building simulation are (a) a family with dependent children where the parents work full time; and (b) a retired elderly couple who spend most of their time indoors. The interview sample from the English Housing Survey 2014–15 was used to map household typologies. Results show that categories (a) and (b) combined amount to only 19% of England’s households, which suggest models are over-reliant on these groups. Considering this result, the paper develops occupancy patterns for England derived from 2015 UK Time Use Survey diaries for each household typology previously identified.     

Sequence analysis of a 14·6 kb DNA fragment of Saccharomyces cerevisiae chromosome VII reveals SEC27, SSM1b,a putative S-adenosylmethionine-dependent enzyme and six new open reading frames

The nucleotide sequence of a fragment from the left arm of Saccharomyces cerevisiae chromosome VII has been determined. Analysis of the 14,607 bp DNA segment reveals nine open reading frames (ORFs) longer than 300 bp. G2827 is the SEC 7 gene, an essential coatomer complex subunit. G2834 encodes SSM1b, a ribosomal protein. The G2838 product shows homology to hypothetical yeast proteins, YIF0 and YE09, of unknown function. The G2830 product shows homology with the cell division protein FtsJ from Escherichia coli, with two hypothetical proteins from yeast, YCF4 and YBR1, and with R74.7, a hypothetical protein from Caenorhabditis elegans. Two of the ORFs are completely internal to longer ones and a third is partially embedded in G2850. The remaining ORFs give no significant homology with proteins in the databases. The sequence has been deposited at the EMBL database under Accession Number X92670.