A water level relationship between consecutive gauge stations along Solim\~oes/Amazonas main channel: a wavelet approach

Gauge stations are distributed along the Solim\~oes/Amazonas main channel to monitor water level changes over time. Those measurements help quantify both the water movement and its variability from one gauge station to the next downstream. The objective of this study is to detect changes in the water level relationship between consecutive gauge stations along the Solim\~oes/Amazonas main channel, since 1980. To carry out the analyses, data spanning from 1980 to 2010 from three consecutive gauges (Tefe, Manaus and Obidos) were used to compute standardized daily anomalies. In particular for infra-annual periods it was possible to detect changes for the water level variability along the Solim\~oes/Amazonas main channel, by applying the Morlet Wavelet Transformation (WT) and Wavelet Cross Coherence (WCC) methods. It was possible to quantify the waves amplitude for the WT infra-annual scaled-period and were quite similar to the three gauge stations denoting that the water level variability are related to the same hydrological forcing functions. Changes in the WCC was detected for the Manaus-Obidos river stretch and this characteristic might be associated with land cover changes in the floodplains. The next steps of this research, will be to test this hypotheses by integrating land cover changes into the floodplain with hydrological modelling simulations throughout the time-series

Microfluidic fabrication of gadolinium-doped hydroxyapatite for theragnostic applications

Among the several possible uses of nanoparticulated systems in biomedicine, their potential as theragnostic agents has received significant interest in recent times. In this work, we have taken advantage of the medical applications of Gadolinium as a contrast agent with the versatility and huge array of possibilities that microfluidics can help to create doped Hydroxyapatite nanoparticles with magnetic properties in an efficient and functional way. First, with the help of Computational Fluid Dynamics (CFD), we performed a complete and precise study of all the elements and phases of our device to guarantee that our microfluidic system worked in the laminar regime and was not affected by the presence of nanoparticles through the flow requisite that is essential to guarantee homogeneous diffusion between the elements or phases in play. Then the obtained biomaterials were physiochemically characterized by means of XRD, FE-SEM, EDX, confocal Raman microscopy, and FT-IR, confirming the successful incorporation of the lanthanide element Gadolinium in part of the Ca (II) binding sites. Finally, the magnetic characterization confirmed the paramagnetic behaviour of the nanoparticles, demonstrating that, with a simple and automatized system, it is possible to obtain advanced nanomaterials that can offer a promising and innovative solution in theragnostic applications.M.S.: R.R. and J.M.R. thank Xunta de Galicia for support (ED431B 2022/36), R.R. is granted by the Program for the requalification, international mobility, and attraction of talent in the Spanish university system, modality Margarita Salas. J.M. and I.F.L. acknowledge support from the Spanish Agencia Estatal de Investigación (project PID2019-104296GB-I00), and I.F.L. from Xunta de Galicia (grant ED481A-2020/149)

Covalent C–N Bond Formation through a Surface Catalyzed Thermal Cyclodehydrogenation

The integration of substitutional dopants at predetermined positions along the hexagonal lattice of graphene-derived polycyclic aromatic hydrocarbons is a critical tool in the design of functional electronic materials. Here, we report the unusually mild thermally induced oxidative cyclodehydrogenation of dianthryl pyrazino[2,3-g]quinoxalines to form the four covalent C–N bonds in tetraazateranthene on Au(111) and Ag(111) surfaces. Bond-resolved scanning probe microscopy, differential conductance spectroscopy, along with first-principles calculations unambiguously confirm the structural assignment. Detailed mechanistic analysis based on ab initio density functional theory calculations reveals a stepwise mechanism featuring a rate determining barrier of only ΔE⧧ = 0.6 eV, consistent with the experimentally observed reaction conditions

Growth Kinetics in a Phase Field Model with Continuous Symmetry

We discuss the static and kinetic properties of a Ginzburg-Landau spherically symmetric $O(N)$ model recently introduced (Phys. Rev. Lett. {\bf 75}, 2176, (1995)) in order to generalize the so called Phase field model of Langer. The Hamiltonian contains two $O(N)$ invariant fields $\phi$ and $U$ bilinearly coupled. The order parameter field $\phi$ evolves according to a non conserved dynamics, whereas the diffusive field $U$ follows a conserved dynamics. In the limit $N \to \infty$ we obtain an exact solution, which displays an interesting kinetic behavior characterized by three different growth regimes. In the early regime the system displays normal scaling and the average domain size grows as $t^{1/2}$, in the intermediate regime one observes a finite wavevector instability, which is related to the Mullins-Sekerka instability; finally, in the late stage the structure function has a multiscaling behavior, while the domain size grows as $t^{1/4}$.Comment: 9 pages RevTeX, 9 figures included, files packed with uufiles to appear on Phy. Rev.

Albumin-based nanoparticles for the delivery of doxorubicin in breast cancer

SIMPLE SUMMARY: Doxorubicin (Dox) is a chemotherapeutic agent usually employed for the treatment of breast cancer. However, its use is limited because of the toxicities associated, and hence a proper delivery vehicle is necessary. In this sense, albumin-based nanocarriers are in the limelight for the successful delivery of chemotherapeutics because of safety, biocompatibility, and specific cancer-targeting properties. Herein, we have developed a nanocarrier system based on albumin, which selectively affects the tumor cells, and hence can revolutionize breast cancer therapy. The developed nanoparticles could be further used for the delivery of other hydrophobic drugs like SN38, which broadens the use of this system in the treatment of breast cancer. ABSTRACT: Albumin-based nanoparticles are an emerging platform for the delivery of various chemotherapeutics because of their biocompatibility, safety, and ease of surface modification for specific targeting. The most widely used method for the preparation of albumin nanoparticles is by desolvation process using glutaraldehyde (GLU) as a cross-linker. However, limitations of GLU like toxicity and interaction with drugs force the need for alternative cross-linkers. In the present study, several cross-linking systems were evaluated for the preparation of Bovine Serum Albumin (BSA) nanoparticles (ABNs) encapsulating Doxorubicin (Dox). Based on the results obtained from morphological characterization, in vitro release, and therapeutic efficacy in cells, N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP)-modified ABNs (ABN-SPDP) was chosen. Since ABN-SPDP are formed with disulfide linkage, the drug release is facilitated under a highly reducing environment present in the tumor sites. The cytotoxicity studies of those ABN-SPDP were performed in three different breast cell lines, highlighting the mechanism of cell death. The Dox-encapsulated ABN-SPDP showed toxicity in both the breast cancer cells (MCF-7 and MDA-MB-231), but, remarkably, a negligible effect was observed in non-tumoral MCF-10A cells. In addition to the hydrophilic Dox, this system could be used as a carrier for hydrophobic drugs like SN38. The system could be employed for the preparation of nanoparticles based on human serum albumin (HSA), which further enhances the feasibility of this system for clinical use. Hence, the albumin nanoparticles developed herein present an excellent potential for delivering various drugs in cancer therapy

Re-entrance and entanglement in the one-dimensional Bose-Hubbard model

Re-entrance is a novel feature where the phase boundaries of a system exhibit a succession of transitions between two phases A and B, like A-B-A-B, when just one parameter is varied monotonically. This type of re-entrance is displayed by the 1D Bose Hubbard model between its Mott insulator (MI) and superfluid phase as the hopping amplitude is increased from zero. Here we analyse this counter-intuitive phenomenon directly in the thermodynamic limit by utilizing the infinite time-evolving block decimation algorithm to variationally minimize an infinite matrix product state (MPS) parameterized by a matrix size chi. Exploiting the direct restriction on the half-chain entanglement imposed by fixing chi, we determined that re-entrance in the MI lobes only emerges in this approximate when chi >= 8. This entanglement threshold is found to be coincident with the ability an infinite MPS to be simultaneously particle-number symmetric and capture the kinetic energy carried by particle-hole excitations above the MI. Focussing on the tip of the MI lobe we then applied, for the first time, a general finite-entanglement scaling analysis of the infinite order Kosterlitz-Thouless critical point located there. By analysing chi's up to a very moderate chi = 70 we obtained an estimate of the KT transition as t_KT = 0.30 +/- 0.01, demonstrating the how a finite-entanglement approach can provide not only qualitative insight but also quantitatively accurate predictions.Comment: 12 pages, 8 figure

Interplay of deep-marine sedimentary processes with seafloor morphology offshore Madeira Island (Central NE-Atlantic)

The deep-water sedimentary processes and morphological features offshore Madeira Island, located in the Central-NE Atlantic have been scantly studied. The analysis of new multibeam bathymetry, echo-sounder profiles and few multichannel seismic reflection profiles allowed us to identify the main geomorphologies, geomorphic processes and their interplay. Several types of features were identified below 3800 m water depth, shaped mainly by i) the interplay between northward-flowing Antarctic Bottom Water (AABW) and turbidity currents and ii) interaction of the AABW with oceanic reliefs and the Madeira lower slope. Subordinate and localized geomorphic processes consist of tectono-magmatic, slope instability, turbidity currents and fluid migration. The distribution of the morphological features defines three regional geomorphological sectors. Sector 1 represents a deep seafloor with its abyssal hills, basement highs and seamounts inherited from Early Cretaceous seafloor spreading. Sector 2 is exclusively shaped by turbidity current flows that formed channels and associated levees. Sector 3 presents a more complex morphology dominated by widespread depositional and erosional features formed by AABW circulation, and localized mixed contourite system developed by the interplay between the AABW circulation and WNW-ESE-flowing turbidite currents. The interaction of the AABW with abyssal hills, seamounts and basement ridges leads to the formation of several types of contourites: patch drifts, double-crest mounded bodies, and elongated, mounded and separated drifts. The patch drifts formed downstream of abyssal hills defining an previously unknown field of relatively small contourites. We suggest they may be a result of localized vortexes that formed when the AABW’s flow impinges these oceanic reliefs producingthe erosional scours that bound these features. The bottom currents in the area are known to be too weak (1–2 cm s− 1) to produce the patch drifts and scours. Therefore, we suggest that these features could be relics at present, having developed when the AABW was stronger than today, as during glacial/end of glacial stages

Sustainable bioethanol production combining biorefinery principles using combined raw materials from wheat undersown with clover-grass

To obtain the best possible net energy balance of the bioethanol production the biomass raw materials used need to be produced with limited use of non-renewable fossil fuels. Intercropping strategies are known to maximize growth and productivity by including more than one species in the crop stand, very often with legumes as one of the components. In the present study clover-grass is undersown in a traditional wheat crop. Thereby, it is possible to increase input of symbiotic fixation of atmospheric nitrogen into the cropping systems and reduce the need for fertilizer applications. Furthermore, when using such wheat and clover-grass mixtures as raw material, addition of urea and other fermentation nutrients produced from fossil fuels can be reduced in the whole ethanol manufacturing chain. Using second generation ethanol technology mixtures of relative proportions of wheat straw and clover-grass (15:85, 50:50, and 85:15) were pretreated by wet oxidation. The results showed that supplementing wheat straw with clover-grass had a positive effect on the ethanol yield in simultaneous saccharification and fermentation experiments, and the effect was more pronounced in inhibitory substrates. The highest ethanol yield (80% of theoretical) was obtained in the experiment with high fraction (85%) of clover-grass. In order to improve the sugar recovery of clover-grass, it should be separated into a green juice (containing free sugars, fructan, amino acids, vitamins and soluble minerals) for direct fermentation and a fibre pulp for pretreatment together with wheat straw. Based on the obtained results a decentralized biorefinery concept for production of biofuel is suggested emphasizing sustainability, localness, and recycling principle

The Cadiz Contourite Channel: Sandy contourites, bedforms and dynamic current interaction

The Cadiz Contourite Channel is the largest and most prominent contourite channel in the middle slope of the Gulf of Cadiz, and is known to channelise the southern branch of the Lower Core of Mediterranean Outflow Water (MOW) as it flows westwards from the Gibraltar Gateway. The channel lies in water depth between 650 and 1500 m, is 150 km long, 2–12 km wide, up to 120 m deep, and broadly s-shaped in plan view. It has several associated subparallel marginal channels and shorter spillover channel segments. Its geometry is controlled by the interaction of a strong bottom current with the seafloor morphology, affected by neotectonic deformation and diapiric intrusion. Bottom photographs and dredge hauls reveal a channel floor shaped by high-energy flow, in places with bare rock, boulders and gravel, and elsewhere covered with sandy contourites. The rocky substrate and derived clasts are formed of authigenic iron-rich carbonates, testifying the high degree of fluid escape from adjacent diapiric ridges and mud volcanoes. The sandy substrate shows a wide range of current-induced bedforms including small, straight-crested ripples, large sinuous sand waves and dunes (wavelength 3.5–5 m, height 0.3–0.9 m), weak surface lineation on sands, and aligned gravel stringers and deep erosive scours around large boulders. Bedform orientation indicates flows directed to the south/south-west (main channel) and west (spillover channel), which can be related to MOW bottom currents, and current velocities that vary between about 0.2 and 0.8 m s− 1, even in the same channel location. However, current vane orientation was clearly responding, at least in part, to tidal effects and periodicity in the Gulf of Cadiz at the time the photographs were taken. Maximum current velocities are achieved by a combination of barotropic and internal tides (probably generated at the continental slope) that reinforce the normal MOW flow. In addition, meteorologically-induced internal waves with periods shorter than tidal ones may exert an even greater influence on current intensity, especially when they occur at times of sudden changes of meteorological forcing. This effect further influences MOW variability. In all cases, the funnelling effect of the Cadiz Channel amplifies tidal or meteorologically-induced bottom currents