The Google Scholar h-index: useful but burdensome metric

Scientometrics - A recent paper in Scientometrics highlighted how the h-index of an academic can be represented differently by different platforms, for example by Web of Science, Scopus, Google...     

3D sound interactive environments for blind children problem solving skills

Audio-based virtual environments have been increasingly used to foster cognitive and learning skills. A number of studies have also highlighted that the use of technology can help learners to develop effective skills such as motivation and self-esteem. This study presents the design and usability of 3D interactive environments for children with visual disabilities to help them solve problems in Chilean geography and culture. We introduce AudioChile, a virtual environment that can be navigated through 3D sound to enhance spatiality and immersion throughout the environment. 3D sound is used to orientate, avoid obstacles, and identify the positions of various characters and objects within the environment. We have found during the usability evaluation that sound can be fundamental for attention and motivation purposes during interaction. Learners identified and clearly discriminated environmental sounds to solve everyday problems, spatial orientation, and laterality.     

Two novel phospholipid fatty acids from the caribbean spongeGeodia gibberosa

The novel fatty acids (Z)-6-nonadecenoic acid (1) and (Z)-17-pentacosenoic acid (2) were characterized in the spongeGeodia gibberosa. These fatty acids were mainly found in phosphatidylethanolamine and phosphatidylcholine.     

NMR and modeling studies of protein-carbohydrate interactions: synthesis, three-dimensional structure, and recognition properties of a minimum hevein domain with binding affinity for chitooligosaccharides

HEV32, a 32-residue, truncated hevein lacking eleven C-terminal amino acids, was synthesized by solid-phase methodology and correctly folded with three cysteine bridge pairs. The affinities of HEV32 for small chitin fragments--in the forms of N,N',N"-triacetylchitotriose ((GlcNAc)3) (millimolar) and N,N',N",N"',N",N"'-hexaacetylchitohexaose ((GlcNAc)6) (micromolar)--as measured by NMR and fluorescence methods, are comparable with those of native hevein. The HEV32 ligand-binding process is enthalpy driven, while entropy opposes binding. The NMR structure of ligand-bound HEV32 in aqueous solution was determined to be highly similar to the NMR structure of ligand-bound hevein. Solvated molecular-dynamics simulations were performed in order to monitor the changes in side-chain conformation of the binding site of HEV32 and hevein upon interaction with ligands. The calculations suggest that the Trp21 side-chain orientation of HEV32 in the free form differs from that in the bound state; this agrees with fluorescence and thermodynamic data. HEV32 provides a simple molecular model for studying protein-carbohydrate interactions and for understanding the physiological relevance of small native hevein domains lacking C-terminal residues.     

Dynamic transitions from smooth to rough to twinning in dislocation motion

The motion of dislocations in response to stress dictates the mechanical behaviour of materials. However, it is not yet possible to directly observe dislocation motion experimentally at the atomic level. Here, we present the first observations of the long-hypothesized kink-pair mechanism in action using atomistic simulations of dislocation motion in iron. In a striking deviation from the classical picture, dislocation motion at high strain rates becomes rough, resulting in spontaneous self-pinning and production of large quantities of debris. Then, at still higher strain rates, the dislocation stops abruptly and emits a twin plate that immediately takes over as the dominant mode of plastic deformation. These observations challenge the applicability of the Peierls threshold concept to the three-dimensional motion of screw dislocations at high strain rates, and suggest a new interpretation of plastic strength and microstructure of shocked metals.     

Development and validation of a high-performance liquid chromatography-mass spectrometry assay for determination of amphetamine, methamphetamine, and methylenedioxy derivatives in meconium

A procedure based on liquid chromatography-mass spectrometry (LC-MS) is described for determination of amphetamine, methamphetamine, and methylendioxy derivatives in meconium, using 3,4-methylendioxypropylamphetamine as internal standard. The analytes were initially extracted from the matrix by 17 mM methanolic HCl. Subsequently, a solid-phase extraction with Bondelut Certify columns was applied. Chromatography was performed on a C(18) reversed-phase column using a linear gradient of 10 mM ammonium bicarbonate, pH 9.0-methanol as a mobile phase. Analytes were determined in LC-MS single ion monitoring mode with an atmospheric pressure ionization-electrospray interface. The method was validated in the range 0.005-1.00 microg/g using 1 g of meconium per assay. Mean recoveries ranged between 61.1 and 87.2% for different analytes. The quantification limits were 0.005 microg/g meconium for amphetamine, methamphetamine, and 4-hydroxy-3-methoxymethamphetamine and 0.004 microg/g meconium for 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyethylamphetamine, and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine. The method was applied to analysis of meconium in newborns to assess eventual fetal exposure to amphetamine derivatives.     

Analog Adaptive Median Filters

The implementation of analog adaptive median filters for image processing is discussed. The adaptive median filter is based on transconductance comparators, whose saturation current is adapted to act as a local weight operator. Transistor level simulations have shown excellent results in removing incidence noise. A 249 × 209 pixel image, corrupted with 35% salt and pepper noise, is used to test the adaptive median filter. All the simulations were made using BSIM3's level 49 model and 1.2 m MOSIS technology parameters.     

Distillation column configurations in ammonia–water absorption refrigeration systems

In ammonia–water absorption refrigeration systems a purification process to reduce the water content in the vapour leaving the generator is required. During this process the water content in the vapour must be reduced to a minimum, otherwise it tends to accumulate in the evaporator and strongly deteriorates the efficiency of the system. The vapour purification can be carried out by partial condensation, by establishing a liquid–vapour counter flow or by combining both methods. In systems with partial condensation, the distillation column can be composed of one or more rectifiers using different cooling mediums, and the rectifying and stripping sections. In complete condensation systems only the rectifying and stripping sections can be used. Therefore different distillation column arrangements should be considered. This paper presents a study of several distillation column configurations for single stage ammonia–water absorption refrigeration systems with partial and complete condensation. In order to evaluate and compare the different configurations, a parameter that indicates the ratio of the ammonia vapour concentration increase in each part of the column to the total ammonia purification has been defined. The analysis has been based on the system COP. Finally the efficiency in each part of the column has been calculated to estimate its design requirements.     

Simultaneous determination of the pesticides carbaryl and thiabendazole in environmental samples by a three-dimensional derivative variable-angle and a synchronous room-temperature phosphorescence spectroscopy

A three-dimensional derivative variable-angle synchronous scanning (DVASS) and a synchronous scanning (SS) heavy-atom room-temperature phosphorimetry (HAI-RTP) method are reported, for the first time, to identify and quantify the spectral overlapping phosphorescent pesticides thiabendazole (TBZ) and carbaryl (CBL). These pesticides are widely used in agriculture. The phosphorescence emission of the two compounds was obtained using sodium sulfite as the O2 scavenger and an external heavy atom salt. A careful selection of these experimental variables has been carried out. The increase of selectivity afforded by the DVASS and the SS methodology permitted the demonstration of its applicability to the simultaneous determination of phosphorescent signals of these two pesticides with overlapping spectral profiles. Limits of detection ranged between 1.4 ng/mL for TBZ and 1.7 ng/mL for CBL. The proposed method has been satisfactorily applied to the analysis of both pesticides in different types of water samples.