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Bixin and norbixin are extracted from annatto seeds, and the residual seed waste can be used as a potential source of annatto starch (AS), contributing to the circular economy of the regional communities where the resource is grown/processed. To assess AS suitability as a food ingredient, its physicochemical, antioxidant, microstructural, and functional properties were evaluated after being purified by: Soaking in sodium metabisulfite solution (low purity), defatting for removing lipids (medium purity), alkaline treatment for extracting protein (medium purity), and combined defatting/alkaline (high purity) treatments. AS degree of purity affected all the evaluated parameters. The ζ-potential values ranged between − 18.30 and − 24.10 mV and those of the antioxidant activity between 0.52 and 1.14 µg TE/g (ABTS•+ assay). AS presented a heterogeneous morphology with granules tending to agglomerate, and the mean Sauter diameter varied from 26.8 to 31.1 µm. FTIR spectroscopy showed that protein molecules were present despite the alkaline treatment. X-ray patterns pinpointed that the starch crystalline region was not modified by the deproteinization treatment. The apparent viscosity and viscoelastic properties of gelatinized starch dispersions increased when lipids and proteins were simultaneously removed. The swelling power (21.44–22.71 g/g), solubility index (21.77–40.43%), water absorption (3.9–4.56 g/g), and oil absorption (1.78–2.41 g/g) increased with the purification degree. The in vitro digestibility assay showed that AS presented a higher fraction of slowly digestible starch (36.57–40.68%) than rapidly digestible and resistant starch fractions. This work demonstrates that AS has suitable functional properties that open the possibility for its use in the food industry.

Brosimum alicastrum is a native tree widely distributed in the Yucatan peninsula where is called Ramon. Some studies have reported that Ramon seeds contain high starch content, recently used in developing novel and sustainable biomaterials. This work aimed to evaluate the effect of the extractive solution on the starch isolation Ramon seed flour; for that, distilled water (S1) and NaOH solution (S2) were used. The Ramon starch yield was 28.0 ± 1.4% and 31.9 ± 1.7% for S1 and S2. The morphology of starches was observed with scanning electronic microscopy, the functional groups were determined through Fourier-transform Infrared Spectroscopy and crystallinity was calculated by X-ray diffraction analysis. The results indicate that both types of starch presented spherical morphology, similar functional groups and crystallinity values, suggesting that both extraction methods are suitable. The starches isolated exhibited similar thermal behavior assessed by differential scanning calorimetry and thermogravimetric analysis.

The biotechnological approach used for pollutants remotion has presented good yields at relatively low cost, nevertheless it still presents a wide margin for improvement to become the principal response to environmental contingencies. As immobilization of microorganisms has demonstrated the decrease of most of the disadvantages of biodegradation, this work aims to briefly review the microorganism’s immobilization for environmental purposes, focusing on encapsulation and exploring its different techniques and carrier materials. The principal reasons to encapsulate microorganisms for bioremediation, the types of capsules and their main characteristics, the physical, chemical, or physicochemical encapsulation methods that have been applied for environmental purposes, and those that have potential in the field, are also revised and explained. The principal biopolymers used to encapsulate and the characteristics they can confer to the capsules. Finally, recent cases of encapsulated microorganisms for bioremediation applications are discussed, highlighting the tendency in the works of the last decade for its application in contaminated waters and the need to explore more carrier materials and encapsulation techniques are also explored.

Understanding charge transport in DNA molecules is a long-standing problem of fundamental importance across disciplines1,2. It is also of great technological interest due to DNA’s ability to form versatile and complex programmable structures. Charge transport in DNA-based junctions has been reported using a wide variety of set-ups2–4, but experiments so far have yielded seemingly contradictory results that range from insulating5–8 or semiconducting9,10 to metallic-like behaviour11. As a result, the intrinsic charge transport mechanism in molecular junction set-ups is not well understood, which is mainly due to the lack of techniques to form reproducible and stable contacts with individual long DNA molecules. Here we report charge-transport measurements through single 30-nm-long double-stranded DNA (dsDNA) molecules with an experimental set-up that enables us to address individual molecules repeatedly and to measure the current–voltage characteristics from 5 K up to room temperature. Strikingly, we observed very high currents of tens of nanoamperes, which flowed through both homogeneous and non-homogeneous base-pair sequences. The currents are fairly temperature independent in the range 5–60 K and show a power-law decrease with temperature above 60 K, which is reminiscent of charge transport in organic crystals. Moreover, we show that the presence of even a single discontinuity (‘nick’) in both strands that compose the dsDNA leads to complete suppression of the current, which suggests that the backbones mediate the long-distance conduction in dsDNA, contrary to the common wisdom in DNA electronics2–4. Measurements of electrical conductance in double-stranded DNA suggest that the backbones mediate the long-distance conduction in dsDNA, contrary to the common wisdom in DNA electronics.

The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion 1-4 . Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions 5-9 has enabled studies of the relationship between thermoelectricity and molecular structure 10,11 . However, observations of Peltier cooling in molecular junctions-a critical step for establishing molecular-based refrigeration-have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy 12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted 2-4,14 .

Nature Communications 8: Article number: 14479 (2017); Published: 15 February 2017; Updated: 25 June 2018 The original HTML version of this Article omitted the article number; it should have been ‘14479’. This has now been corrected in the HTML version of the Article. The PDF version was correct from the time of publication.

Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer.

Thermal radiative emission from a hot surface to a cold surface plays an important role in many applications, including energy conversion, thermal management, lithography, data storage and thermal microscopy. Recent studies on bulk materials have confirmed long-standing theoretical predictions indicating that when the gap between the surfaces is reduced to tens of nanometres, well below the peak wavelength of the blackbody emission spectrum, the radiative heat flux increases by orders of magnitude. However, despite recent attempts, whether such enhancements can be obtained in nanoscale dielectric films thinner than the penetration depth of thermal radiation, as suggested by theory, remains experimentally unknown. Here, using an experimental platform that comprises a heat-flow calorimeter with a resolution of about 100 pW (ref. 7), we experimentally demonstrate a dramatic increase in near-field radiative heat transfer, comparable to that obtained between bulk materials, even for very thin dielectric films (50-100 nm) when the spatial separation between the hot and cold surfaces is comparable to the film thickness. We explain these results by analysing the spectral characteristics and mode shapes of surface phonon polaritons, which dominate near-field radiative heat transport in polar dielectric thin films.

We study theoretically the electronic and transport properties of a diffusive superconductor-normal metal-superconductor (SNS) junction in the presence of a perpendicular magnetic field. We show that the field dependence of the critical current crosses over from the well-known Fraunhofer pattern in wide junctions to a monotonic decay when the width of the normal wire is smaller than the magnetic length \(\xi_{\mathrm{H}}=\sqrt{\varPhi_{0}/H}\) , where H is the magnetic field and Φ0 the flux quantum. We demonstrate that this behavior is intimately related to the appearance of a linear array of vortices in the middle of the normal wire, the properties of which are very similar to those in the mixed state of a type II superconductor. This novel vortex structure is also manifested in a strong modulation of the local density of states along the transversal dimension, which can be measured with existing experimental techniques.

Background Pemphigus vulgaris is a chronic autoimmune bullous disease, the initiation of autoimmunity has been linked to viral infections. In 1974, Krain first reported the association between herpes simplex virus and pemphigus vulgaris, since then, there have been few such studies, prompting us to examine this link. Findings We randomly selected 15 cases of PV, the diagnosis was confirmed using hematoxylin and eosin (H&E)-stained slides—2-micron sections were deparaffinized and rehydrated to be processed by immunohistochemistry, antigen retrieval was performed with 0.1 % sodium citrate, pH 6.2, endogenous peroxidase was inactivated with 0.9 % H2O2, and washes were performed with distilled water. Finally the slides were allowed to stand for 5 min in phosphate-buffered saline (PBS). The tissues were incubated for 45 min with polyclonal anti-HSV-I, (1:150, Dako Corporation, Carpinteria, CA). The MACH 1 system was applied for 15 min to visualize the reaction using 3,3′-diaminobenzidine-H2O2 (both from Biocare Medical) as substrate under a microscope. The tissues were counterstained with Lillie-Mayer’s hematoxylin (Biocare Medical). We failed to observe positivity for HSV-1 in any of the 15 PV cases that were processed. Conclusions It is not possible to determine whether HSV-PV is a causal relationship; most studies are case reports. Thus, we propose research studies with greater methodological weight to determine the involvement of HSV in the pathogenesis of PV and demonstrate that the relationship between HSV-1 and PV is a trigger at the beginning of the disease and has an etiologic function in its pathogenesis or that it is merely a coinfection due to the immunosuppression of patients with PV.

Single-molecule junctions with high rectification ratios can be realized by exposing different electrode surface areas to an ionic liquid.

Fabrication of structures at the atomic scale is now possible using state-of-the-art techniques for manipulating individual atoms1, and it may become possible to design electrical circuits atom by atom. A prerequisite for successful design is a knowledge of the relationship between the macroscopic electrical characteristics of such circuits and the quantum properties of the individual atoms used as building blocks. As a first step, we show here that the chemical valence determines the conduction properties of the simplest imaginable circuit—a one-atom contact between two metallic banks. The extended quantum states that carry the current from one bank to the other necessarily proceed through the valence orbitals of the constriction atom. It thus seems reasonable to conjecture that the number of current-carrying modes (or ‘channels’) of a one-atom contact is determined by the number of available valence orbitals, and so should strongly differ for metallic elements in different series of the periodic table. We have tested this conjecture using scanning tunnelling microscopy and mechanically controllable break-junction techniques2,3 to obtain atomic-size constrictions for four different metallic elements (Pb, Al, Nb and Au), covering a broad range of valences and orbital structures. Our results demonstrate unambiguously a direct link between valence orbitals and the number of conduction channels in one-atom contacts.