Sap is clever? Sap ascent for undergraduates investigated with an artificial tree

Water is the essential component in living and its role is particularly important in plants. In fact, the crucial photosynthesis process involves a huge loss of sap by transpiration (around 99% from the total amount recovered from the soil through the plant roots) from the stomas on the leaves. Therefore, a question arises: How could trees raise the sap to heights up to 100 m? In this article we present a simple experimental setup that provides a direct visualization and quantification of the water ascent process against gravity. Moreover, the artificial tree offers analogies with "real" ones that will help undergraduate science students from different areas to investigate the influence of environmental and morphological parameters on the variety of physics phenomena underlying the ascension mechanis

Low-cost and biodegradable thermoelectric devices based on van der Waals semiconductors on paper substrates

We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates. The devices are based on thin films of WS2, Te, and BP (P-type semiconductors) and TiS3 and TiS2 (N-type semiconductors), deposited by simply rubbing powder of these materials against paper. The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of (+1.32 ± 0.27) mV/K and (-0.82 ± 0.15) mV/K for WS2 and TiS3, respectively. Additionally, Peltier elements were fabricated by interconnecting the P-type and N-type films with graphite electrodes. A thermopower value up to 6.11 mV/K was obtained when the Peltier element is constructed with three junctions. The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic device

Research and development of hydrogen carrier based solutions for hydrogen compression and storage

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Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectives

Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications. With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus. In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized. In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles. In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage”, different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.Fil: Bellosta von Colbe, Jose. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Ares Fernández, José Ramón. Universidad Autónoma de Madrid; EspañaFil: Jussara, Barale. Università di Torino; ItaliaFil: Baricco, Marcello. Università di Torino; ItaliaFil: Buckley, Craig E.. Curtin University; AustraliaFil: Capurso, Giovanni. Helmholtz Zentrum Geesthacht; AlemaniaFil: Gallandat, Noris. GRZ Technologies Ltd; SuizaFil: Grant, David M.. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino Unido. University of Nottingham; Estados UnidosFil: Guzik, Matylda N.. University of Oslo; NoruegaFil: Jacob, Isaac. Ben Gurion University of the Negev; IsraelFil: Jensen, Emil H.. University of Oslo; NoruegaFil: Jensen, Torben. University Aarhus; DinamarcaFil: Jepsen, Julian. Helmholtz Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmholtz Zentrum Geesthacht; AlemaniaFil: Lototskyy, Mykhaylol V.. University of Cape Town; SudáfricaFil: Manickam, Kandavel. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Montone, Amelia. Casaccia Research Centre; ItaliaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Helmholtz Zentrum Geesthacht; AlemaniaFil: Sartori, Sabrina. University of Oslo; NoruegaFil: Sheppard, Drew A.. Curtin University; AustraliaFil: Stuart, Alastair. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Walker, Gavin. University of Nottingham; Estados Unidos. Science and Technology Facilities Council of Nottingham. Rutherford Appleton Laboratory; Reino UnidoFil: Webb, Colin J.. Griffith University; AustraliaFil: Yang, Heena. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Yartys, Volodymyr. Institute for Energy Technology; NoruegaFil: Züttel, Andreas. Empa Materials Science & Technology; Suiza. École Polytechnique Fédérale de Lausanne; SuizaFil: Dornheim, Martin. Helmholtz Zentrum Geesthacht; Alemani

Alcohol-related liver disease phenotype impacts survival after an acute variceal bleeding episode

[Background & Aims] Alcohol-related hepatitis (AH) encompasses a high mortality. AH might be a concomitant event in patients with acute variceal bleeding (AVB). The current study aimed to assess the prevalence of AH in patients with AVB and to compare the clinical outcomes of AH patients to other alcohol-related liver disease (ALD) phenotypes and viral cirrhosis.[Methods] Multicentre, observational study including 916 patients with AVB falling under the next categories: AH (n = 99), ALD cirrhosis actively drinking (d-ALD) (n = 285), ALD cirrhosis abstinent from alcohol (a-ALD) (n = 227) and viral cirrhosis (n = 305). We used a Cox proportional hazards model to calculate adjusted hazard ratio (HR) of death adjusted by MELD.[Results] The prevalence of AH was 16% considering only ALD patients. AH patients exhibited more complications. Forty-two days transplant-free survival was worse among AH, but statistical differences were only observed between AH and d-ALD groups (84 vs. 93%; p = 0.005), when adjusted by MELD no differences were observed between AH and the other groups. At one-year, survival of AH patients (72.7%) was similar to the other groups; when adjusted by MELD mortality HR was better in AH compared to a-ALD (0.48; 0.29–0.8, p = 0.004). Finally, active drinkers who remained abstinent presented better survival, independently of having AH.[Conclusions] Contrary to expected, AH patients with AVB present no worse one-year survival than other patients with different alcohol-related phenotypes or viral cirrhosis. Abstinence influences long-term survival and could explain these counterintuitive results.Meritxell Ventura-Cots is a recipient of Juan Rodés grant from the Instituto de Salud Carlos III (ISCIII), Joan Genescà is a recipient of grants PI18/00947 and PI21/00691 from ISCIII.Peer reviewe

Tribochemical Decomposition of Light Ionic Hydrides at Room Temperature

Tribochemical decomposition of magnesium hydride (MgH2) induced by deformation at room temperature was studied on a micrometric scale, in situ and in real time. During deformation, a near-full depletion of hydrogen in the micrometric affected zone is observed through an instantaneous (t < 1 s) and huge release of hydrogen (3–50 nmol/s). H release is related to a nonthermal decomposition process. After deformation, the remaining hydride is thermally decomposed at room temperature, exhibiting a much slower rate than during deformation. Confocal-microRaman spectroscopy of the mechanically affected zone was used to characterize the decomposition products. Decomposition was enhanced through the formation of the distorted structure of MgH2 with reduced crystal size by mechanical deformation.We acknowledge financial support from the Ministry of Economy and Competitiveness of Spain through the grants RYC-2009-0412, BIA-2011-25653, and IPT-2012-1167-120000 with participation of the European Regional Development Fund (FEDER) as well as MINECO 2011-22780 and MAT2013-48009-C4-1-P

An XPS investigation on the influence of the substrate and growth conditions on pyrite thin films surface composition

Pyrite thin films have been prepared by sulfuration of Fe thin films deposited on sodalime glass substrates. Sulfuration temperatures have ranged from 200 °C to 500 °C and sulfuration time has been 20 h in all cases. It has been found that, during the sulfuration process, Na from the substrate diffuses through the formed pyrite thin film and reaches its surface where it reacts with some components of the sulfuration atmosphere to form sodium sulfate (NaSO). The Na concentration at the film surface has been measured as a function of the film sulfuration temperature. Obtained experimental data show that Na surface concentration increases up to a sulfuration temperature of 350 °C but, on passing from this temperature to 400 °C, a drastic reduction is produced. For higher sulfuration temperatures (T > 400 ° C) the Na surface concentration slightly increases. Besides, a chemical variation of the pyrite surface composition related to an excess of sulfur is measured as a function of the sulfuration temperature showing a quite parallel behavior to that shown by the Na surface concentration. This excess of sulfur appears regardless the type of substrate (sodalima glass, alumina or amorphous quartz) used. The obtained results have been correlated with the variations of other parameters (grain and crystallite size, thickness, etc.) of the sulfurated films. After these investigations, it has been concluded that the Na concentration evolution at the film surface closely reflects the pyrite thin film grain crystallization (and size) which takes place during the sulfuration process. As a consequence, it is proposed that a change of the Na diffusion mechanism through the film (from diffusion through the grain boundaries to diffusion through the grain bulk) takes place at the indicated critical sulfuration temperatures. The reported excess of sulfur might be also related to this crystallization, although no further evidence has been obtained from our results. The consequences of this conclusion are discussed on the light of present pyrite thin film knowledge, mainly those aspects concerning to possible doping effects of Na and electrical transport processes in pyrite thin films.The authors thank technical support from Mr. F. Moreno. Financial support by MINECO-FEDER (MAT2015-65203R) is acknowledged and the project INFANTE (PIE 201550E072) is also recognized. Carlos Morales thanks the Ministerio de Educación Cultura y Deporte of Spain for the FPU grant

Pyrethroid insecticide lambda-cyhalothrin induces hepatic cytochrome P450 enzymes, oxidative stress and apoptosis in rats

This study aimed to examine in rats the effects of the Type II pyrethroid lambda-cyhalothrin on hepatic microsomal cytochrome P450 (CYP) isoform activities, oxidative stress markers, gene expression of proinflammatory, oxidative stress and apoptosis mediators, and CYP isoform gene expression and metabolism phase I enzyme PCR array analysis. Lambda-cyhalothrin, at oral doses of 1, 2, 4 and 8 mg/kg bw for 6 days, increased, in a dose-dependent manner, hepatic activities of ethoxyresorufin O-deethylase (CYP1A1), methoxyresorufin O-demethylase (CYP1A2), pentoxyresorufin O-depentylase (CYP2B1/2), testosterone 7α- (CYP2A1), 16β-(CYP2B1), and 6β-hydroxylase (CYP3A1/2), and lauric acid 11- and 12-hydroxylase (CYP4A1/2). Similarly, lambda-cyhalothrin (4 and 8 mg/kg bw, for 6 days), in a dose-dependent manner, increased significantly hepatic CYP1A1, 1A2, 2A1, 2B1, 2B2, 2E1, 3A1, 3A2 and 4A1 mRNA levels and IL-1β, NFκB, Nrf2, p53, caspase-3 and Bax gene expressions. PCR array analysis showed from 84 genes examined (P b 0.05; fold change N 1.5), changes in mRNA levels in 18 genes: 13 up-regulated and 5 down-regulated. A greater fold change reversion than 3-fold was observed on the up-regulated ALDH1A1, CYP2B2, CYP2C80 and CYP2D4 genes. Ingenuity Pathway Analysis (IPA) groups the expressed genes into biological mechanisms that aremainly related to drug metabolism. In the top canonical pathways, Oxidative ethanol degradation III together with Fatty Acid α-oxidation may be significant pathways for lambda-cyhalothrin. Our results may provide further understanding of molecular aspects involved in lambda-cyhalothrin-induced liver injury.Comunidad de Madrid (S2013/ABI-2728)Ministerio de Economía, Industria y Competitividad (RTA2015-00010-C03-03)Depto. de Farmacología y ToxicologíaFac. de VeterinariaTRUEpu

High Current Density Electrical Breakdown of TiS₃ Nanoribbon-Based Field-Effect Transistors

The high field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, the high current density properties of the layered material titanium trisulfide (TiS3) are studied here. The high breakdown current densities of up to 1.7 × 106 A cm−2 are observed in TiS3 nanoribbon-based field-effect transistors, which are among the highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for current breakdown, a thermogravimetric analysis of bulk TiS3 is performed and the results with density functional theory and kinetic Monte Carlo calculations are compared. In conclusion, the oxidation of TiS3 and subsequent desorption of sulfur atoms play an important role in the electrical breakdown of the material in ambient conditions. The results show that TiS3 is an attractive material for high power applications and lend insight into the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.Accepted Author ManuscriptQN/van der Zant La