Predicting the size and morphology of nanoparticle clusters driven by biomolecular recognition.

Nanoparticle aggregation is a driving principle of innovative materials and biosensing methodologies, improving transduction capabilities displayed by optical, electrical or magnetic measurements. This aggregation can be driven by the biomolecular recognition between target biomolecules (analytes) and receptors bound onto nanoparticle surface. Despite theoretical advances on modelling the entropic interaction in similar systems, predictions of the fractal morphologies of the nanoclusters of bioconjugated nanoparticles are lacking. The morphology of resulting nanoclusters is sensitive to the location, size, flexibility, average number of receptors per particle f̄, and the analyte-particle concentration ratio. Here we considered bioconjugated iron oxide nanoparticles (IONPs) where bonds are mediated by a divalent protein that binds two receptors attached onto different IONPs. We developed a protocol combining analytical expressions for receptors and linker distributions, and Brownian dynamics simulations for bond formation, and validated it against experiments. As more bonds become available (e.g., by adding analytes), the aggregation deviates from the ideal Bethe's lattice scenario due to multivalence, loop formation, and steric hindrance. Generalizing Bethe's lattice theory with a (not-integer) effective functionality feff leads to analytical expressions for the cluster size distributions in excellent agreement with simulations. At high analyte concentration steric impediment imposes an accessible limit value facc to feff, which is bounded by facc < feff < f̄. A transition to gel phase, is correctly captured by the derived theory. Our findings offer new insights into quantifying analyte amounts by assessing nanocluster size, and predicting nanoassembly morphologies accurately is a first step towards understanding variations of physical properties in clusters formed after biomolecular recognition.

Functional characterization of a Cold-In place-Recycled pavement at different stages of the curing process.

Cold-In place-Recycled (CIR) pavements are an environmentally friendly option for road rehabilitation operations on aged pavements. These pavements are generally employed as base layers, and a surface treatment is performed on them. However, the design of new additives and enhancements in the technique for constructing CIR pavements have enabled such pavements to be used as wearing courses in some cases. In this context, research on the functional characteristics of CIR pavements is required for characterizing their performance and, therefore, broaden their knowledge and use as a noise mitigation measure. The aim of this study is to analyze some of these functional characteristics: tire/pavement sound levels, texture, and dynamic stiffness. An experimental test track section was evaluated during the pavement curing process (very short term) by means of laboratory and field auscultation. Different measurement campaigns were conducted at different stages of the pavement curing process. According to our results, the changes in the pavement during curing lead to higher tire/pavement sound levels due to the evolution of the dynamic stiffness of the pavement. The increase in tire/pavement noise levels is mainly located at the peak frequencies (800-1250 Hz) of the sound spectra, with values from 76.2 dB(A) to 81.5 dB(A) at 800 Hz. The differences among the mean values of the macrotexture (Mean Profile Depth - MPD) do not explain the different overall tire/pavement noise levels measured at the different stages of curing. However, the texture spectrum undergoes an evolution. The initial texture levels, with wavelengths between 100 mm and 500 mm decrease during the curing process.

Introduction to Nanomaterials Applied to Life Sciences.

A. Espinosa, F. J. Teran and D. Ortega introduce the Nanoscale Advances themed collection on Nanomaterials Applied to Life Sciences.

Dynamic stiffness of road pavements: Construction characteristics-based model and influence on tire/road noise.

Tire/pavement noise is produced by the interaction between a tire and the road surface. Complex noise generation mechanisms are involved in this process. Dynamic stiffness (or mechanical impedance) is considered as a related reduction/amplification mechanism. Despite its potential importance, in conventional hot bituminous mixtures this mechanism has little influence on tire/pavement noise. This is because the dynamic stiffness of tire treads is significantly lower than that of the hot bituminous mixes (conventional road surfaces). This paper presents a field assessment of the dynamic stiffness of five experimental sections with different characteristics: from the environmentally friendly mixes such as the Cold-In place-Recycled (CIR) pavement to the gap graded hot bituminous mixtures with crumb rubber (CR) from end of life tires (ELTs). The obtained dynamic stiffness spectra are fitted using a Boltzmann Sigmoid function. The relationships between the fitting coefficients and a few pavement construction characteristics are assessed in order to model the pavement dynamic stiffness as a function of these characteristics. In addition to dynamic stiffness, several surface characteristics such as the Close ProXimity (CPX) sound levels from the tire/pavement interaction, macrotexture in terms of the Mean Profile Depth (MPD), unevenness in terms of the International Roughness Index (IRI), and acoustic absorption are studied. According to our results, lower dynamic stiffness values are related to lower noise levels at high frequencies. No relationship was observed between the low dynamic stiffness values and noise attenuation at medium frequencies in this research work.

Species-specific alterations in Anopheles mosquito olfactory responses caused by Plasmodium infection.

Mosquitoes infected with malaria parasites have demonstrated altered behaviour that may increase the probability of parasite transmission. Here, we examine the responses of the olfactory system in Plasmodium falciparum infected Anopheles gambiae, Plasmodium berghei infected Anopheles stephensi, and P. berghei infected An. gambiae. Infected and uninfected mosquitoes showed differential responses to compounds in human odour using electroantennography coupled with gas chromatography (GC-EAG), with 16 peaks triggering responses only in malaria-infected mosquitoes (at oocyst, sporozoite or both stages). A selection of key compounds were examined with EAG, and responses showed differences in the detection thresholds of infected and uninfected mosquitoes to compounds including lactic acid, tetradecanoic acid and benzothiazole, suggesting that the changes in sensitivity may be the reason for differential attraction and biting at the oocyst and sporozoite stages. Importantly, the different cross-species comparisons showed varying sensitivities to compounds, with P. falciparum infected An. gambiae differing from P. berghei infected An. stephensi, and P. berghei infected An. gambiae more similar to the P. berghei infected An. stephensi. These differences in sensitivity may reflect long-standing evolutionary relationships between specific Plasmodium and Anopheles species combinations. This highlights the importance of examining different species interactions in depth to fully understand the impact of malaria infection on mosquito olfactory behaviour.

Emergency electroencephalogram: Usefulness in the diagnosis of nonconvulsive status epilepticus by the on-call neurologist. / Uso de la electroencefalografía urgente por el neurólogo de guardia: utilidad en el diagnóstico del estatus epiléptico no convulsivo.

INTRODUCTION: We aim to describe the use of emergency electroencephalogram (EmEEG) by the on-call neurologist when nonconvulsive status epilepticus (NCSE) is suspected, and in other indications, in a tertiary hospital. SUBJECTS AND METHODS: Observational retrospective cohort study of emergency EEG (EmEEG) recordings with 8-channel systems performed and analysed by the on-call neurologist in the emergency department and in-hospital wards between July 2013 and May 2015. Variables recorded were sex, age, symptoms, first diagnosis, previous seizure and cause, previous stroke, cancer, brain computed tomography, diagnosis after EEG, treatment, patient progress, routine control EEG (rEEG), and final diagnosis. We analysed frequency data, sensitivity, and specificity in the diagnosis of NCSE. RESULTS: The study included 135 EEG recordings performed in 129 patients; 51.4% were men and their median age was 69 years. In 112 cases (83%), doctors ruled out suspected NCSE because of altered level of consciousness in 42 (37.5%), behavioural abnormalities in 38 (33.9%), and aphasia in 32 (28.5%). The EmEEG diagnosis was NCSE in 37 patients (33%), and this was confirmed in 35 (94.6%) as the final diagnosis. In 3 other cases, NCSE was the diagnosis on discharge as confirmed by rEEG although the EmEEG missed this condition at first. EmEEG performed to rule out NCSE showed 92.1% sensitivity, 97.2% specificity, a positive predictive value of 94.6%, and a negative predictive value of 96%. CONCLUSIONS: Our experience finds that, in an appropriate clinical context, EmEEG performed by the on-call neurologist is a sensitive and specific tool for diagnosing NCSE.

Unraveling viscosity effects on the hysteresis losses of magnetic nanocubes.

Hysteresis losses in magnetic nanoparticles constitute the basis of magnetic hyperthermia for delivering a local thermal stress. Nevertheless, this therapeutic modality is only to be realised through a careful appraisal of the best possible intrinsic and extrinsic conditions to the nanoparticles for which they maximise and preserve their heating capabilities. Low frequency (100 kHz) hysteresis loops accurately probe the dynamical magnetic response of magnetic nanoparticles in a more reliable manner than calorimetry measurements, providing conclusive quantitative data under different experimental conditions. We consider here a set of iron oxide or cobalt ferrite nanocubes of different sizes, through which we experimentally and theoretically study the influence of the viscosity of the medium on the low frequency hysteresis loops of magnetic colloids, and hence their ability to produce and dissipate heat to the surroundings. We analyse the role of nanoparticle size, size distribution, chemical composition, and field intensity in making the magnetisation dynamics sensitive to viscosity. Numerical simulations using the stochastic Landau-Lifshitz-Gilbert equation model the experimental observations in excellent agreement. These results represent an important contribution towards predicting viscosity effects and hence to maximise heat dissipation from magnetic nanoparticles regardless of the environment.

Effects of inter- and intra-aggregate magnetic dipolar interactions on the magnetic heating efficiency of iron oxide nanoparticles.

Iron oxide nanoparticles have found an increasing number of biomedical applications as sensing or trapping platforms and therapeutic and/or diagnostic agents. Most of these applications are based on their magnetic properties, which may vary depending on the nanoparticle aggregation state and/or concentration. In this work, we assess the effect of the inter- and intra-aggregate magnetic dipolar interactions on the heat dissipation power and AC hysteresis loops upon increasing the nanoparticle concentration and the hydrodynamic aggregate size. We observe different effects produced by inter- (long distance) and intra-aggregate (short distance) interactions, resulting in magnetizing and demagnetizing effects, respectively. Consequently, the heat dissipation power under alternating magnetic fields strongly reflects such different interacting phenomena. The intra-aggregate interaction results were successfully modeled by numerical simulations. A better understanding of magnetic dipolar interactions is mandatory for achieving a reliable magnetic hyperthermia response when nanoparticles are located into biological matrices.

Assessment of an action against environmental noise: Acoustic durability of a pavement surface with crumb rubber.

Environmental noise is a worldwide problem that has an adverse effect in the quality of life of urban population. Some work has shown that there is a correlation between environmental noise and health issues as sleep disturbance or annoyance. This study presents the time evolution of a test track fabricated with an asphalt mixture with 20% of crumb rubber by weight of bitumen, added by the wet process. A complete surface characterization has been performed by determining tire/pavement sound levels, road texture profiles, in-situ dynamic stiffness and sound absorption of compacted and extracted sample cores. Two measurement campaigns were performed: just after mixture laying and after 3 years in service. This study confirms that the use of crumb rubber as a modifier of bituminous binders (CRMB) can improve the pavement characteristics: gap-graded mixtures with crumb rubber can be used in the action plans as urban rehabilitation measure to fight noise pollution. However, this noise reduction seems to decrease with age at a rate of approximately 0.15 dB(A) per year.

Toward the acoustical characterization of asphalt pavements: analysis of the tire/road sound from a porous surface.

Sound level in close proximity to the contact patch of the tire and road (L(CPtr)) is analyzed as a function of the vehicle speed in the acoustic frequency range, showing different behavior depending on frequency. At least two regions are observed; one at low frequencies, where the variation in sound with speed (coefficient B) increases with frequency, and the other at higher frequencies, where such sound/speed variation does not increase significantly with frequency. The dependence of B at low frequencies seems to be correlated with the high sound absorption of this porous surface.

Assessment of asphalt concrete acoustic performance in urban streets.

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of streets with low speed limits is presented for a reference speed of 50 km/h. Different pavements and pavement conditions, common in urban streets, are analyzed: dense and semidense asphalt concrete, with Spanish denomination D-8 and S-12, respectively, and on the other hand, dense pavement at the end of its service life (D-8(*)). From the acoustics point of view, the most favorable surface, by more than 4 dB(A) compared with the S-12 mix, is the smoothest surface, i.e., the D-8 mix, even though it presents a minor absorption coefficient in normal incidence. Noise levels from dense surfaces (D-8) increase significantly over time, principally due to the appearance of surface defects such as cracks and ruts. Longitudinal variability of the close proximity tire/pavement noise emission and surface homogeneity are also analyzed.

Monitoring road surfaces by close proximity noise of the tire/road interaction.

Applied acoustics is becoming an important field for civil infrastructure and environmental assessment, and road maintenance or rehabilitation strategies. In this research LA(2)IC has developed a GPS-based measurement techniques and apparatus on a test vehicle, for monitoring the acoustical properties of different road pavement surfaces with a reference tire. A field test on PA-12 Spanish porous pavement found in Ciudad Real is developed. The test procedure, a modification based upon the close-proximity method (CPX), relies on the use of three standard microphones situated very close to the tire/road contact patch. This procedure allows the simultaneous measurement of the sound emission synchronized to a GPS receiver, which permits tracking of the position of the sound emission. Geo-referenced sound spectra for every 10 m during individual passes of the test vehicle are analyzed to determine the tire/road noise emissions from tire/PA-12 pavement interaction. Noise levels of around 102 dB(A), with a variability of approximately 0.6 dB(A), are found at a reference vehicle speed of 85 kmh. The frequency spectrum analysis over the test section shows noticeable differences for frequencies above 1 kHz, where the tire/road noise generation mechanisms are dominated by air pumping.

Collective character of spin excitations in a system of Mn2+ spins coupled to a two-dimensional electron gas.

We have studied the low energy spin excitations in n-type CdMnTe based dilute magnetic semiconductor quantum wells. For magnetic fields for which the energies for the excitation of free carriers and Mn spins are almost identical, an anomalously large Knight shift is observed. Our findings suggest the existence of a magnetic-field-induced ferromagnetic order in these structures, which is in agreement with recent theoretical predictions [Phys. Rev. Lett. 91, 077202 (2003)]].

Microbial and physiological characterization of weakly amylolytic but fast-growing lactic acid bacteria: a functional role in supporting microbial diversity in pozol, a Mexican fermented maize beverage.

Pozol is an acid beverage obtained from the natural fermentation of nixtamal (heat- and alkali-treated maize) dough. The concentration of mono- and disaccharides from maize is reduced during nixtamalization, so that starch is the main carbohydrate available for lactic acid fermentation. In order to provide some basis to understand the role of amylolytic lactic acid bacteria (ALAB) in this fermented food, their diversity and physiological characteristics were determined. Forty amylolytic strains were characterized by phenotypic and molecular taxonomic methods. Four different biotypes were distinguished via ribotyping; Streptococcus bovis strains were found to be predominant. Streptococcus macedonicus, Lactococcus lactis, and Enterococcus sulfureus strains were also identified. S. bovis strain 25124 showed extremely low amylase yield relative to biomass (139 U g [cell dry weight](-1)) and specific rate of amylase production (130.7 U g [cell dry weight](-1) h(-1)). In contrast, it showed a high specific growth rate (0.94 h(-1)) and an efficient energy conversion yield to bacterial cell biomass (0.31 g of biomass g of substrate(-1)). These would confer on the strain a competitive advantage and are the possible reasons for its dominance. Transient accumulation of maltooligosaccharides during fermentation could presumably serve as energy sources for nonamylolytic species in pozol fermentation. This would explain the observed diversity and the dominance of nonamylolytic lactic acid bacteria at the end of fermentation. These results are the first step to understanding the importance of ALAB during pozol fermentation.

Pauli paramagnetism and Landau level crossing in a modulation doped CdMnTe/CdMgTe quantum well.

Electrical transport measurements are reported on a 2DEG in a CdMnTe quantum well structure. The amplitude of the Shubnikov-de Haas oscillations show a distinct beating pattern with nodes corresponding to coincidences between the spin splitting and a half integer multiple of the cyclotron energy. The observed pattern of nodes is a direct consequence of the large Pauli paramagnetism induced by the s-d exchange interaction between the spins of electronic states and the localized magnetic moments.

Enzymatic extraction and transformation of glucovanillin to vanillin from vanilla green pods.

Glucovanillin was extracted from green pods and simultaneously transformed to vanillin by a combination of enzyme activities involving cell wall degradation and glucovanillin hydrolysis. The reaction is best carried out with 47.5% v/v aqueous ethanol solution during 8 h at 70 degrees C, in a two-step enzymatic reaction using Viscozyme followed by Celluclast, two commercial enzymatic products containing mainly pectinase and cellulase activities, respectively. The extractive reaction proceeded with high efficiency with an amount of extracted vanillin 3.13 times higher than the one obtained with the Soxhlet method. The classical curing/extraction process results in 1.1-1.8 g of vanillin/100 g of dry pods. It is concluded that the enzymatic reaction may substitute the microbial process involved in tissue fermentation previous to vanillin extraction with the simultaneous hydrolysis of glucovanillin.

A pectate lyase from Zinnia elegans is auxin inducible.

The Zinnia mesophyll cell system consists of isolated leaf mesophyll cells in culture that can be induced, by auxin and cytokinin, to reproducibly trans-differentiate into tracheary elements (TE) after 96 h, while in the presence of auxin alone the cells simply elongate. In a search for genes involved in modifications to cell-wall architecture before any overt signs of cell differentiation, a differential hybridization of a 72-h cDNA library with probes from mRNA at time-points of 24 h and 72 h was done revealing a number of transcripts up-regulated between these times. One of these cDNAs shows homology to pectate lyase, a pectin-degrading enzyme. The complete cDNA sequence (ZePel) corresponds to a translated protein of 44 kDa with an N-terminal signal peptide of about 2 kDa, and one potential N-glycosylation site. Northern analysis confirms that the strong expression of this gene during TE induction occurs at a very early stage of the process and is due solely to the presence of auxin in the induction medium. In situ hybridization studies in young Zinnia stems show that ZePel expression is associated with vascular bundles and shoot primordia. Recombinant protein made in Escherichia coli possesses calcium-dependent pectate lyase activity. Pectate lyase activity is detected in elongating and differentiating in vitro cell populations. The role of this enzyme in remodelling the cell wall during cell elongation and differentiation is discussed.

[Total congenital absence of left pericardium in 3 cases]. / Ausencia congénita total de pericardio izquierdo en 3 casos.

Congenital absence of left pericardium is rare. We report three adult women, mean age 48 years old, in which this diagnosis was confirmed. This condition must be suspected in patients with atypical chest pain, as in 2 of our cases, or in the presence of radiologic cardiomegaly of unknown origin, as in the third case. Physical examination may disclose a left displaced cardiac apex and electrocardiogram a right axis deviation, incomplete right bundle branch block and clockwise rotation. Chest X rays show a left displaced heart with a prominent pulmonary artery and the interposition of pulmonary flap between the aorta and pulmonary artery and between left hemidiaphragm and lower cardiac border. There is an echocardiographic impression of left chamber enlargement and the usual apical, four chamber vision is observed placing the transductor in posterior positions. The diagnosis could be confirmed with computed tomography and magnetic resonance imaging.