Water flow enhancement in hydrophilic nanochannels

All published reports on fluid flow enhancement and water slippage are associated with hydrophobic surfaces, such as carbon nanotubes. Here, we investigate water flow in hydrophilic alumina nanochannels with diameters ranging from 20 nm to 100 nm. For the smallest channels tested, the water permeability is more than double than the theoretical prediction using the Hagen-Poiseuille equation. Though such an enhancement is significantly smaller than what has been measured in carbon nanotubes, it clearly shows that flow enhancement and water slippage occurs on hydrophilic surfaces as well, contrary to existing theoretical models. To the authors' knowledge, it is the first experimental demonstration of water slippage on hydrophilic surfaces. The results show the dependence of the flow enhancement on the surface chemistry, diameter and length of the nanochannel.     

A comparative study on the effects of three commercial Ti–B-based grain refiners on the impact properties of A356 cast aluminium alloy

The effect of three commercial Ti–B-based grain refiners on the impact properties of the A356 cast aluminium alloy was assessed. The impact tests were performed by means of an instrumented Charpy pendulum. During impact testing, the maximum load and the total impact energy, as well as its complementary contributions, the energy at maximum load and the crack propagation energy, were measured. Impact properties were studied as a function of size and shape of the main microstructural features, which were analysed by means of optical microscopy and scanning electron microscopy. The results show that the influence of grain refinement on microstructure involves beneficial and detrimental concurrent effects which strongly affect impact properties. The total impact energy decreases with the addition of all the grain refiners due to a shift from a mixed transgranular–intergranular fracture mode to a more severe transgranular mode. Crack initiation and propagation occur mainly through the fracture of Fe-intermetallics and brittle Si particles, and the mechanism of void coalescence. No direct correlation between grain size and impact properties is found. Moreover, the aspect ratio of eutectic Si particles does not change with grain refinement, implying that there are no mutual poisoning effects between Sr and B. Total impact energy is found to depend on both SDAS and β-platelets size. The concurrent effects of SDAS and β-platelets average maximum length on total impact energy can be taken into account by the multiple regression analysis technique.     

Fluorination of suspended graphene

Nano Research - Suspended graphene is exposed to different fluorine-containing species produced by a plasma source fed with CF4 precursor gas. We investigate the fluorination process by selecting...     

Diagnostic and Prognostic Role of Extracellular Vesicles in Pancreatic Cancer: Current Evidence and Future Perspectives

Pancreatic cancer is one of the most aggressive tumors, with a dismal prognosis due to poor detection rates at early stages, rapid progression, post-surgical complications, and limited effectiveness of conventional oncologic therapies. There are no consistently reliable biomarkers or imaging modalities to accurately diagnose, classify, and predict the biological behavior of this tumor. Therefore, it is imperative to develop new and improved strategies to detect pancreatic lesions in the early stages of cancerization with greater sensitivity and specificity. Extracellular vesicles, including exosome and microvesicles, are membrane-coated cellular products that are released in the outer environment. All cells produce extracellular vesicles; however, this process is enhanced by inflammation and tumorigenesis. Based on accumulating evidence, extracellular vesicles play a crucial role in pancreatic cancer progression and chemoresistance. Moreover, they may represent potential biomarkers and promising therapy targets. The aim of the present review is to review the current evidence on the role of extracellular vesicles in pancreatic cancer.     

Stereoselective Access to Antimelanoma Agents by Hybridization and Dimerization of Dihydroartemisinin and Artesunic acid

A library of five hybrids and six dimers of dihydroartemisinin and artesunic acid has been synthetized in a stereo-controlled manner and evaluated for the anticancer activity against metastatic melanoma cell line (RPMI7951). Among novel derivatives, three artesunic acid dimers showed antimelanoma activity and cancer selectivity, being not toxic on normal human fibroblast (C3PV) cell line. Among the three dimers, the one bearing 4-hydroxybenzyl alcohol as a spacer showed no cytotoxic effect (CC₅₀>300 μM) and high antimelanoma activity (IC₅₀=0.05 μM), which was two orders of magnitude higher than that of parent artesunic acid, and of the same order of commercial drug paclitaxel. In addition, this dimer showed cancer-type selectivity towards melanoma compared to prostate (PC3) and breast (MDA-MB-231) tumors. The occurrence of a radical mechanism was hypothesized by DFO and EPR analyses. Qualitative structure activity relationships highlighted the role of artesunic acid scaffold in the control of toxicity and antimelanoma activity.     

Parameter Estimation of the Transient Storage Model for Stream–Subsurface Exchange

The transient storage model (TSM) is the most commonly used model for stream–subsurface exchange of solutes. The TSM provides a convenient, simplified representation of hyporheic exchange, but its lack of a true physical basis causes its parameters to be difficult to predict. However, the simple formulation makes the model a useful practical tool for many applications. This work compares the TSM with a physically based pumping model. This comparison is advantageous for two reasons: Advective pumping is known to be an important hyporheic exchange process in many streams, and the pumping model can be used to derive dimensionless transient storage parameters that are properly scaled with important physical stream parameters. Transient storage model parameters are shown to be dependent on both the timescale of observation and the shape of the breakthrough curve, i.e., on the temporal evolution of the solute concentration in the surface water. This indicates that the transient storage model can, in practice, lead to incorrect predictions when model parameters are obtained without consideration of the stream flow dynamics, the properties of the stream bed, or the process timescale. This work emphasizes the limitations of simplified models for hyporheic transport, and indicates that such models need to be carefully applied.     

Reactive navigation through multiscroll systems: from theory to real-time implementation

In this paper a new reactive layer for multi-sensory integration applied to robot navigation is proposed. The new robot navigation technique exploits the use of a chaotic system able to be controlled in real-time towards less complex orbits, like periodic orbits or equilibrium points, considered as perceptive orbits. These are subject to real-time modifications on the basis of environment changes acquired through a distributed sensory system. The strategy is inspired to the olfactory bulb neural activity observed in rabbits subject to external stimuli. The mathematical details of the approach are given including simulation results in a virtual environment. Furthermore the proposed strategy has been tested on an experimental environment consisting of an FPGA-based hardware driving an autonomous roving robot. The obtained results demonstrate the capability to perform a real-time navigation control.