Josephson-like tunnel resonance and large Coulomb drag in GaAs-based electron-hole bilayers

Bilayers consisting of two-dimensional (2D) electron and hole gases separated by a 10 nm thick AlGaAs barrier are formed by charge accumulation in epitaxially grown GaAs. Both vertical and lateral electric transport are measured in the millikelvin temperature range. The conductivity between the layers shows a sharp tunnel resonance at a density of $1.1 \cdot 10^{10} \text{ cm}^{-2}$, which is consistent with a Josephson-like enhanced tunnel conductance. The tunnel resonance disappears with increasing densities and the two 2D charge gases start to show 2D-Fermi-gas behavior. Interlayer interactions persist causing a positive drag voltage that is very large at small densities. The transition from the Josephson-like tunnel resonance to the Fermi-gas behavior is interpreted as a phase transition from an exciton gas in the Bose-Einstein-condensate state to a degenerate electron-hole Fermi gas

Strongly interacting 2D electron systems: Evidence for enhanced 1D edge-channel coupling

We observe nearly vanishing Hall resistances for integer filling factors in a counterflow (CF) experiment on a density balanced 2D bilayer system. Filling factor dependent equilibration lengths demonstrate enhanced 1D coupling via edge-channels. Due to the narrow barrier the edge-modes of the two 2DEGs are in close proximity allowing for 1D excitonic correlations. Electron drag measurements confirm the observed quantum state selective coupling between the layers

Il trattamento conservativo precoce nella Camptodattilia = Camptodactyly : early nonoperative treatment

Scopo: Approfondimento delle classificazioni e dei protocolli conservativi utilizzati dalle unit\ue0 operative di chirurgia della mano e pubblicati negli ultimi 15 anni. Confronto con la classificazione ed il protocollo utilizzati nel nostro reparto. Materiali e metodi: Si sono analizzati i protocolli conservativi pubblicati e si \ue8 poi descritto il nostro protocollo attraverso l\u2019analisi di tre casi attualmente in trattamento. Risultati: Si \ue8 evidenziata una disomogeneit\ue0 nella classificazione delle camptodattilie e nell\u2019utilizzo dei tutori, sia per tipologia che per modalit\ue0 di utilizzo. Il nostro reparto si avvale della classificazione di Foucher per determinare la scelta del tipo di tutore. Conclusioni: Anche se la tipologia di tutore non \ue8 sempre la stessa, tutti gli autori concordano che, nella maggioranza delle camptodattilie sia importante cominciare con l\u2019approccio conservativo. Nel nostro reparto vengono confezionati tutori statici o dinamici in base al tipo di camptodattilia e viene monitorato costantemente l\u2019andamento tramite misurazioni goniometriche, con ottimi risultati.Purpose: To analyse the classifications and the conservative protocols used by hand surgery operative\u2019s units and published in the last 15 years. To draw a comparison between those classifications and protocols and the ones used in our unit. Material and Methods: The published conservative treatments have been analysed and then our protocol has been described through the analysis of three cases currently treated in our division. Results: It has been highlighted that camptodactyly classifications are not homogeneous. Moreover, in conservative treatment, different typology and posology of splints have been adopted. Our unit uses the Foucher\u2019s classification to define the type of splint that it is necessary. Conclusions: Despite the authors choose different types of splint, they agree that in the most cases of camptodactily the initial approach is conservative. In our unit static and dynamic splints are made directly on the patient\u2019s hand and they are monitored with goniometrical measurements, obtaining great results

Quantifying Biomolecular Binding Constants Using Video Paper Analytical Devices

A novel ultra‐low‐cost biochemical analysis platform to quantify protein dissociation binding constants and kinetics using paper microfluidics is reported. This approach marries video imaging with one of humankind's oldest materials: paper, requiring no large, expensive laboratory equipment, complex microfluidics or external power. Temporal measurements of nanoparticle–antibody conjugates binding on paper is found to follow the Langmuir Adsorption Model. This is exploited to measure a series of antibody–antigen dissociation constants on paper, showing excellent agreement with a gold‐standard benchtop interferometer. The concept is demonstrated with a camera and low‐end smartphone, 500‐fold cheaper than the reference method, and can be multiplexed to measure ten reactions in parallel. These findings will help to widen access to quantitative analytical biochemistry, for diverse applications spanning disease diagnostics, drug discovery, and environmental analysis in resource‐limited settings

A novel ratiometric fluorescent approach for the modulation of the dynamic range of lateral flow immunoassays

The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application

Annexin-V/quantum dot probes for multimodal apoptosis monitoring in living cells : Improving bioanalysis using electrochemistry

There is a great demand to develop novel techniques that allow useful and complete monitoring of apoptosis, which is a key factor of several diseases and a target for drug development. Here, we present the use of a novel dual electrochemical/optical label for the detection and study of apoptosis. We combined the specificity of Annexin-V for phosphatidylserine, a phospholipid expressed in the outer membrane of apoptotic cells, with the optical and electrochemical properties of quantum dots to create a more efficient label. Using this conjugate we addressed three important issues: (i) we made the labeling of apoptotic cells faster (30 min) and easier; (ii) we fully characterized the samples by common cell biological techniques (confocal laser scanning microscopy, scanning electron microscopy and flow cytometry); and (III) we developed a fast, cheap and quantitative electrochemical detection method for apoptotic cells with results in full agreement with those obtained by flow cytometry

Tuneable Plasmonic Gold Dendrimer Nanochains for Sensitive Disease Detection

We report the development of a tuneable plasmonic nanochain immunoassay with increased sensitivity over traditional monodisperse nanoparticle lateral flow tests. Our approach takes advantage of the unique self-assembling properties of polyamidoamine dendrimers with gold nanoparticles in aqueous media to create one-dimensional nanochains, with a distinct red to blue colour change, attributable to a longitudinal plasmon resonance, which can be readily detected by eye and a digital camera. We optimise and characterise nanochain formation and stability using UV-visible spectroscopy, transmission electron microscopy and dynamic light scattering. As a proof-of-principle we focus on the application of nanochains for point-of-care diagnostics for p24, an important biomarker of early HIV infections and successfully detect p24 with a limit of detection of 5 ng ml−1 in pseudo-serum, 4 fold more sensitive than comparable studies with gold nanoparticles. These findings and underlying concepts highlight the potential of advanced functional organic–inorganic composite nanomaterials to diagnose infections, with broad applicability to non-communicable diseases

Compuestos y reacciones quimicas naturales como motivadores del aprendizaje

Uno de los componentes importantes en el proceso de aprendizaje, se relaciona con la fuerte motivación intrínseca que el estudiante muestra hacia los contenidos que debe incorporar. Mas allá de los intereses propios de los alumnos es posible aportar, desde los materiales didácticos con los cuales se trabaja en el aula, información, imágenes, e inquietudes que, al relacionarse con temas aplicados de su entorno natural conduzcan a un aumento en la atención, como modo de mejorar la comprensión, retención y posterior uso activo de los conocimientos adquiridos (Teoría Uno, Perkins, 1995). En esta propuesta el aprendizaje de la escritura de fórmulas y ecuaciones químicas, con todos sus componentes asociados se presenta como material didáctico que describe compuestos y reacciones químicas observables en el entorno natural circundante del alumno

Compuestos y reacciones quimicas naturales como motivadores del aprendizaje

Uno de los componentes importantes en el proceso de aprendizaje, se relaciona con la fuerte motivación intrínseca que el estudiante muestra hacia los contenidos que debe incorporar. Mas allá de los intereses propios de los alumnos es posible aportar, desde los materiales didácticos con los cuales se trabaja en el aula, información, imágenes, e inquietudes que, al relacionarse con temas aplicados de su entorno natural conduzcan a un aumento en la atención, como modo de mejorar la comprensión, retención y posterior uso activo de los conocimientos adquiridos (Teoría Uno, Perkins, 1995). En esta propuesta el aprendizaje de la escritura de fórmulas y ecuaciones químicas, con todos sus componentes asociados se presenta como material didáctico que describe compuestos y reacciones químicas observables en el entorno natural circundante del alumno

Functional Active Microbiome in Supragingival Biofilms in Health and Caries

The oral microbiome is unique at inter and intra-individual levels at various sites due to physical and biological factors. This study aimed to compare the bacterial composition of supragingival biofilms collected from enamel sites with different caries activity, from active and inactive-caries subjects, and from caries-free (CF) subjects. Twenty-two individuals (aged between 13 and 76 years old; med = 23.5 years old) were allocated into 3 groups: caries-active (CA) (n = 10), caries-inactive (CI) (n = 6), and CF (n = 6). From the CA group, 3 sites were sampled: CA (active non-cavitated lesion), CI (inactive non-cavitated lesion), and sound enamel surface (S). From the subjects of the CI group, biofilm from a CI lesion was collected (INCL), while for the CF subjects, a pool of biofilm from sound enamel surfaces was sampled. The total RNA was extracted, and cDNA libraries were prepared and pairedend sequenced (Illumina HiSeq 3,000). Final dental biofilm samples analysed from CA was 16 (ANCL-CA = 6, INCL-CA = 4, S-CA = 6); from CI, 3 (INCL-CI = 3); and from CF, 6 (S-CF = 6) (some samples were lost by insufficient genetic material). Read sequences were processed and analysed using the Metagenomics RAST server. High-quality sequences (3,542,190) were clustered into operational taxonomic units (97% identity; SILVA SSU), representing 915 genera belonging to 29 phyla (higher abundant: Actinobacteria, Firmicutes, Bacteroidetes, and Fusobacteria). The presence of a core microbiome was observed (123 shared genera). The alpha diversity analysis showed less bacterial diversity in disease (S-CA) compared to health (S-CF). The dominant genera included Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, Veillonella, Prevotella, Streptococcus, Eubacterium, and Neisseria. Veillonella and Leptotrichia were related with disease and Prevotella with health. Corynebacterium, Capnocytophaga, and Actinomyces clustered together presenting high abundance in health and disease. The Metric Multidimensional Scaling Ordination analysis shows that sites from active subjects (ANCL-CA, INCL-CA, and S-CA) are closer to each other than either INCL-CI subjects or S-CF subjects. In conclusion, supragingival bacterial communities presented intra-individual similarities, but inter-individual diversity and difference in bacterial composition reveal that the subject’s caries activity status matters more than sites