Ketogenic diet-fed rats have increased fat mass and phosphoenolpyruvate carboxykinase activity

The ketogenic diet (KD), characterized by high fat and low carbohydrate and protein contents, has been proposed to be beneficial in children with epilepsy disorders not helped by conventional anti-epileptic drug treatment. Weight loss and inadequate growth is an important drawback of this diet and metabolic causes are not well characterized. The aim of this study was to examine body weight variation during KD feeding for 6 wk of Wistar rats; fat mass and adipocyte cytosolic phosphoenolpyruvate carboxykinase (PEPCK) activity were also observed. PEPCK activity was determined based on the [H(14)CO(3) (-)]-oxaloacetate exchange reaction. KD-fed rats gained weight at a less rapid rate than normal-fed rats, but with a significant increment in fat mass. The fat mass/body weight ratio already differed between ketogenic and control rats after the first week of treatment, and was 2.4 x higher in ketogenic rats. The visceral lipogenesis was supported by an increment in adipocyte PEPCK, aiming to provide glycerol 3-phosphate to triacylglycerol synthesis and this fat accumulation was accompanied by glucose intolerance. These data contribute to our understanding of the metabolic effects of the KD in adipose tissue and liver and suggest some potential risks of this diet, particularly visceral fat accumulation.     

Investigation of the thin film crystallization of a DNA copolymer hybrid composed of chitosan

We describe for the first time the crystallization in thin films of a DNA copolymer composed of a low molecular weight chitosan backbone to which a sequence of nucleic acids is grafted (chitosan‐g‐ssDNA). As assessed by atomic force microscopy, optical microscopy and spectroscopy, crystallization occurs due to intermolecular hydrogen bonding in which the nucleic acid strands engage. The morphology of the crystals depends on the affinity for the surface of the polymer segments that compose the DNA copolymer hybrid. The nucleic acids adsorb on mica and silica on which side‐branched structures are observed whereas chitosan interacts preferentially with gold, and dendritic crystals are assembled. Attenuated total reflectance infrared spectroscopy supports the high ordering of the structure and the establishment of strong intermolecular interactions by hydrogen bonding. © 2016 Society of Chemical Industry     

An analysis for solar central receiver systems with terminal concentrators or variable apertures

A central receiver system, having a downlooking cavity and a field of focusing heliostats, is analyzed in the absence and in the presence of a terminal concentrator. Researches compared calculated collector performance to the given characteristics determined by Ref. [2], at a specific site location of Sandia Laboratory, Albuquerque. New Mexico. This study presents a proposal for a central receiver cavity with an irised aperture. Concentration ratios and efficiencies were obtained for comparison with a fixed aperture system. The proposed system demonstrates improved performance. If the advantages of the system over the lifetime of the installation proved to outweigh the disadvantages of the extra cost and complexity, the proposed design would be desirable.     

Paramagnetism and Superconductivity in Eu<Subscript>0.7</Subscript>Sm<Subscript>0.3</Subscript>Ba<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−δ</Subscript>

Magnetic properties of sintered Eu_0.7Sm_0.3Ba₂Cu₃O_7?δ were investigated both in dc and ac magnetic fields. The dc response reflects the interplay between the rare earth ion paramagnetic and the superconducting charge carrier subsystems, respectively. The harmonic susceptibilities exhibit special features: the second harmonic is anomalously high and the third harmonic in zero dc-field has reversed temperature dependence with respect to the theoretical models. The magnetic relaxation at low fields is monotonous and occurs as a two-stage relaxation, each stage obeying logarithmical time dependence with different rates. At high fields, the relaxation is nonmonotonous with a peak at intermediate time suggesting a temporary re-entrance of irreversibility when the flux-line density increases in the center of the sample because of the redistribution of the vortices toward that region.     

Tests on the photomultiplier Burle C83061E for underground physics applications

In this article we describe the main results of the test activity performed on the large cathode area phototube Burle C83061E. This tube, originally developed for a large-scale Cherenkov detector, has been considered as a potential candidate for the use in the proposed low energy solar neutrino experiment Borexino. Thus the measurements carried out have been particularly focused to evaluate the parameters of this device more critically affecting the overall physics performances of the detector.     

Mechanics of fibre fragmentation

A fragmentation specimen consists of a single fibre embedded along the axis of a long narrow resin block. When the fibre is broken by a tensile load, either a lateral crack runs outwards into the resin, initiated by the break, or a debond (or equivalently a cylindrical crack in the resin) propagates along the fibre. Debonding always occurs with thin fibres. Strain energy release rates have now been calculated, analytically for long debonds and by FEA for short ones. The force to propagate a debond is found to increase as the debond grows, reaching a final value, termed pull-out force, that is higher for softer fibres. If this force exceeds the strength of the fibre, then the fibre breaks again. This is the proposed mechanism of fibre fragmentation. For weakly-bonded, stiff fibres, the inferred minimum distance between breaks, i.e. the critical fragment length, is deduced to be of the order of the geometric mean of the radii of fibre and resin block, about 0.1–0.5 mm for typical fragmentation specimens, and it increases as the ratio of fibre stiffness to resin block stiffness increases, in agreement with observation.     

Autophagy as an ultrastructural marker of heavy metal toxicity in human cord blood hematopoietic stem cells

Stem cells are a key target of environmental toxicants, but little is known about their toxicological responses. We aimed at developing an in-vitro model based on adult human stem cells to identify biomarkers of heavy metal exposure. To this end we investigated the responses of human CD34+ hematopoietic progenitor cells to hexavalent chromium (Cr[VI]) and cadmium (Cd). Parallel cultures of CD34+ cells isolated from umbilical cord blood were exposed for 48 h to 0.1 microM and 10 microM Cr(VI) or Cd. Cultures treated with 10 microM Cr(VI) or Cd showed marked cell loss. Ultrastructural analysis of surviving cells revealed prominent autophagosomes/autophagolysosomes, which is diagnostic of autophagy, associated with mitochondrial damage and replication, dilatation of the rough endoplasmic reticulum and Golgi complex, cytoplasmic lipid droplets and chromatin condensation. Treated cells did not show the morphologic hallmarks of apoptosis. Treatment with 0.1 microM Cr(VI) or Cd did not result in cell loss, but at the ultrastructural level cells showed dilated endoplasmic reticulum and evidence of mitochondrial damage. We conclude that autophagy is implicated in the response of human hematopoietic stem cells to toxic concentrations of Cr(VI) and Cd. Autophagy, which mediates cell survival and death under stress, deserves further evaluation to be established as biomarker of metal exposure.     

New daylight fluorescent pigments

The synthesis and properties of a series of plastosoluble daylight fluorescent pigments based on benzanthrone, 1-azabenzanthrone, 14H-[2,1,9-mna]thioxanthene-14-one and its 5-aza analogue are reported.     

DDoS protection with stateful software‐defined networking

Distributed denial of service (DDoS) attacks represent one of the most critical security challenges facing network operators. Software‐defined networking (SDN) permits fast reactions to such threats by dynamically enforcing simple forwarding/blocking rules as countermeasures. However, the centralization of the control plane requires that the SDN controller, besides network management operations, should also collect information to identify and mitigate the security menaces. A major drawback of this approach is that it may overload the controller and the control channel. On the other hand, stateful SDN represents a new concept, developed to improve reactivity and offload the controller by delegating local treatments to the switches. In this article, we embrace this paradigm to protect end‐hosts from DDoS attacks. We propose StateSec, a novel approach based on in‐switch processing capabilities to detect and mitigate flooding threats. StateSec monitors packets matching configurable traffic features without resorting to the controller. By feeding an entropy‐based detection algorithm with such monitoring features, it detects and mitigates several threats such as (D)DoS with high accuracy. We implemented StateSec in an SDN platform comparing it with state‐of‐the‐art approaches. We show that StateSec is far more efficient: It achieves very accurate detection levels, reducing at the same time the control plane overhead. We have also evaluated the memory footprint of StateSec for a possible use in production. Finally, we deployed StateSec over a real network to tune its parameters and assess its suitability to real‐world deployments.