495 research outputs found

    NTrw StAw Processions of gods in the Book of the Day An iconographical study

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    This thesis is a careful study of all the iconographic aspects of the processions of gods rerpresented in the book of the Day. Comparing the different sources, it has been possible to create clusters of divinities and to classify them according to their function within the diurnal solar journey. Of fundamental importance has been the study of the tomb of Ramose Tt 132. The careful analysis of the iconographical programme of this unpublished tomb has enabled the author to identify cluster of divinities in KV 9 and attempt a subdivision of the divinities depicted on the walls of the royal tombs. This thesis has also shown that in the study of the NK Books of the Netherworld the iconographical aspect is as important as the filological one

    A stabilized formulation with maximum entropy meshfree approximants for viscoplastic flow simulation in metal forming

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    The finite element method is the reference technique in the simulation of metal forming and provides excellent results with both Eulerian and Lagrangian implementations. The latter approach is more natural and direct but the large deformations involved in such processes require remeshing-rezoning algorithms that increase the computational times and reduce the quality of the results. Meshfree methods can better handle large deformations and have shown encouraging results. However, viscoplastic flows are nearly incompressible, which poses a challenge to meshfree methods. In this paper we propose a simple model of viscoplasticity, where both the pressure and velocity fields are discretized with maximum entropy approximants. The inf-sup condition is circumvented with a numerically consistent stabilized formulation that involves the gradient of the pressure. The performance of the method is studied in some benchmark problems including metal forming and orthogonal cutting

    Fully Printed Flexible Ultrasound Transducer for Medical Applications

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    The fabrication of a fully printed, lead-free, polymer piezoelectric transducer is presented and the characterization of its structural, dielectric, and ferroelectric properties at different processing stages is demonstrated. The performance of poly(vinylidene fluoride-trifluoroethylene) transducers with resonance frequency analyses, acoustic power measurements, and pulse-echo experiments is evaluated. Notably, for the first time for a fully printed transducer, an optimal performance in the medical ultrasound range (<15 MHz) is demonstrated with acoustic power >1 W cm(-2), which is promising for applications in epidermal and wearable electronics. Overall, the findings provide a strong foundation for future research in the area of flexible ultrasound transducers

    Operating Conditions Affecting the Behavior of Wheat Straw Pellets During Slow Pyrolysis Process: a Full Insight

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    A deep study on the effects of absolute pressure, peak temperature, gas residence time and gas atmosphere on the pyrolysis behaviour of wheat straw pellets in a bench-scale fixed-bed reactor has been carried out

    Flexible In-Ga-Zn-O thin-film transistors with sub-300-nm channel lengths defined by two-photon direct laser writing

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    In this work, the low-temperature (≤ 150 °C) fabrication and characterization of flexible Indium-Gallium-ZincOxide (IGZO) top-gate thin-film transistors (TFTs) with channel lengths down to 280 nm is presented. Such extremely short channel lengths in flexible IGZO TFTs were realized with a novel manufacturing process combining two-photon direct laser writing (DLW) photolithography with Ti/Au/Ti source/drain e-beam evaporation and lift-off. The resulting flexible IGZO TFTs exhibit a saturation field-effect mobility of 1.1 cm2V -1 s -1 and a threshold voltage of 3 V. Thanks to the short channel lengths (280 nm) and the small gate to source/drain overlap (5.2 µm), the TFTs yield a transit frequency of 80 MHz (at 8.5 V gate-source voltage) extracted from the measured S-parameters. Furthermore, the devices are fully functional when wrapped around a cylindrical rod with 6 mm radius, corresponding to 0.4 % tensile strain in the TFT channel. These results demonstrate a new methodology to realize entirely flexible nano-structures, and prove its suitability for the fabrication of short-channel transistors on polymer substrates for future wearable communication electronics

    Manually curated and harmonised transcriptomics datasets of psoriasis and atopic dermatitis patients

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    We present manually curated transcriptomics data of psoriasis and atopic dermatitis patients retrieved from the NCBI Gene Expression Omnibus and EBI ArrayExpress repositories. We collected 39 transcriptomics datasets, deriving from DNA microarrays and RNA-Sequencing technologies, for a total of 1677 samples. We provide quality-checked, homogenised and preprocessed gene expression matrices and their corresponding metadata tables along with the estimated surrogate variables. These data represent a ready-made valuable source of knowledge for translational researchers in the dermatology field.Peer reviewe

    Preliminary study on the influence of pyrolysis process conditions on the textural properties of activated carbons from wheat straw-derived biochars

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    It is widely known that biochar can be used in a wide range of applications including —but not limited to— soil amendment, energy production, adsorption and catalysis [1]. For the last two final uses, however, the pristine biochar produced through pyrolysis processes does not have an appropriate porosity development. In fact, the porosity of biochar is mainly due to narrow micropores[2]. Therefore, an activation process is needed to develop a more hierarchical porous structure in order to facilitate the diffusion path of the corresponding adsorbates and/or reactants. To date, there is almost no research on how the pyrolysis process conditions, at which the biochar precursors are produced, can affect the porosity of the subsequent activated biochars. The aim of this work is to evaluate how the slow pyrolysis process conditions adopted for the production of biochars from wheat straw pellets can affect the textural properties of the final activated carbons, which are obtained via physical activation with CO2 at 800 °C of the raw biochars. For this purpose, the following operating parameters were selected: the absolute pressure (from 0.2 to 0.9 MPa), the pyrolysis peak temperature (from 400 to 550 °C), and the type of gas atmosphere during pyrolysis (pure N2 or a binary mixture of CO2 and N2 60:40 v/v). Not only the main effect of these parameters individually but also the possible effects derived from the interactions between them have been considered. To this aim, an unreplicated 2-level factorial design has been adopted to objectively analyze the influence of these parameters on the response variables (i.e., the BET specific surface area, pore volumes, and pore size distribution of the physically activated biochars). The wheat straw-derived biochars were produced through slow pyrolysis in a bench-scale fixed-bed reactor, made of stainless steel and electrically heated. More details regarding the reactor configuration are available in a previous publication [3]. Then, the produced raw pellet-shaped biochars were crushed and sieved to obtain particle sizes within the range of 0.212–1.41 mm. For the subsequent physical activation, around 20 g of pristine biochar was heated up to 800 °C in a fixed-bed reactor placed within a tubular furnace (model EVA 12/300 from Carbolite Gero, UK) under pure N2 atmosphere and at atmospheric pressure. Once this temperature was reached, the inlet gas stream was switched from N2 to pure CO2. During the reaction step, both the soaking time and gas-hourly space velocity were kept constant at 1 h and 7000 h–1, respectively. Under these conditions, the degree of burn-off of the produced activated biochar could be dependent on the intrinsic reactivity and porous structure of the precursor. The textural properties of both raw and activated biochars have been determined from the adsorption isotherms of N2 at –196 °C and CO2 at 0° C. The activation tests are almost finished and the results obtained will be presented during the course of the conference. References [1] Liu, W.-J., Jiang, H.; Yu, H.-Q. Chem. Rev. 2015, 115, 12251–12285. [2] Manyà, J. J., González, B., Azuara, M.; Arner, G. Chem. Eng. J. 2018, 345, 631–639. [3] Greco, G., Videgain, M., Di Stasi, C., González, B.; Manyà, J. J. J. Anal. Appl. Pyrolysis 2018, 136, 18–26

    Effects of slow-pyrolysis conditions on the products yields and properties and on exergy efficiency: A comprehensive assessment for wheat straw

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    In the present work, the effects of the peak temperature (400–550 °C), absolute pressure (0.2–0.9 MPa), gas residence time (100–200 s) and reactor atmosphere (pure N2 or a mixture of CO2/N2) on the pyrolysis behavior of wheat straw pellets were investigated. A factorial design of experiments was adopted to assess the effects of the above-mentioned factors on the pyrolysis products, the exergy efficiencies related to them and to the overall process, and the heat required. The pyrolysis energy/exergy assessment is nowadays of great interest, for the scaling of the installations from lab-scale to commercial-scale. Results showed that, as expected, the peak temperature was the most influential factor on the yields and distributions of all the pyrolysis products as well as the char properties related to its potential stability and pore size distribution. However, an increased pressure enhanced the release of the gas species at the expense of the liquid products, without altering the final char yield. The char exergy efficiency was negatively affected by an increase in peak temperature, whereas its effect on the exergy efficiency of the produced gas resulted to be positive. It was also found that pressurized pyrolysis favored the exergy efficiency of the process, even at relatively high pyrolysis peak temperature. For the biomass feedstock and the range of operating conditions studied here, thermodynamic irreversibilities of the pyrolysis system were considerably lowered when the process was conducted at 550 °C, 0.9 MPa and using a mixture of CO2 and N2 as carrier gas at relatively short residence times

    Physically activated wheat straw-derived biochar for biomass pyrolysis vapors upgrading with high resistance against coke deactivation

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    Wheat straw-derived biochars (produced through slow pyrolysis at 500 degrees C and 0.1 MPa) were physically (with CO2) and chemically (with K2CO3) activated to assess their performance as renewable and low-cost catalysts for biomass pyrolysis vapors upgrading. Preliminary cracking experiments, which were carried out at 700 degrees C using a mixture of four representative model compounds, revealed a clear correlation between the volume of micropores of the catalyst and the total gas production, suggesting that physical activation up to a degree of burn-off of 40% was the most interesting activation route. Next, steam reforming experiments were conducted using the most microporous material to analyze the effect of both the bed temperature and gas hourly space velocity (GHSV) on the total gas production. The results showed a strong dependence between the bed temperature and the total gas production, with the best result obtained at the highest temperature (750 degrees C). On the other hand, the change in GHSV led to minor changes in the total gas yield, with a maximum achieved at 14500 h(-1). Under the best operating conditions deduced in the previous stages, the addition of CO2 into the feed gas stream (partial pressure of 20 kPa) resulted in a total gas production of 98% with a H-2/CO molar ratio of 2.16. This good result, which was also observed during the upgrading of the aqueous phase of a real biomass pyrolysis oil, was ascribed to the relatively high coke gasification rate, which refresh the active surface area preventing deactivation by coke deposition

    Assessment of the effect of pyrolysis operating conditions on phytotoxicity and potential as carrier for AM fungi of vine shoots-derived biochar

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    Biochar production from vine shoots appears as an interesting option to manage this agricultural waste for both environmental and agronomic benefits. In order to produce biochar from biomass at appropriate yields, slow pyrolysis is a particularly suitable option. However, the properties of the resulting biochar strongly depend on the process operating conditions. In this sense, establishing the most appropriate operating conditions is still required with the aim at producing engineered biochars. Furthermore, it should be kept in mind that a certain compromise between the pyrolysis operating conditions and the expected properties of biochar has to be achieved. In other words, the most appropriate conditions to produce a biochar with the desired properties for a given purpose might not be suitable for another one (e.g., pyrolysis conditions leading to a maximization of the carbon sequestration potential can result in biochars with high phytotoxicity and thus not suitable for soil amendment purposes). The highest temperature reached in the pyrolysis process (i.e., peak temperature) has proven to be a fundamental parameter in determining the physicochemical properties as well as the potential stability of biochar [1]. Nevertheless, few earlier studies have focused on assessing the combined effect of both the absolute pressure and residence time of the vapor phase within the reactor [2]. In light of the above-mentioned considerations, the specific aim of this study is to analyze the effect of the peak temperature (350–500 °C), absolute pressure (0.1–0.5 MPa), and residence time of the vapor phase (50–150 s) on the distribution of pyrolysis products and key properties of produced biochar. In addition to the assessment of the potential stability of biochar (which can be related to its fixed-carbon content and atomic H:C and O:C ratios), its potential toxicity on seed germination as well as its interaction with arbuscular mycorrhizal (AM) fungi were also evaluated. A 2-level factorial design (with the addition of three replicates at the center point) was adopted to objectively analyze the effect of the selected factors on the response variables. Pyrolysis experiments were conducted in a batch fixed-bed reactor, the details of which are available elsewhere [2]. The content of water in the total condensable fraction was measured using a Karl-Fischer volumetric titrator from Metrohm (Switzerland). The composition of the gas fraction (N2, CO2, CO, CH4, C2Hx and H2) was determined using a micro-GC 490 from Agilent (USA). The initial sample mass of biomass was approximately 500 g. The raw biomass was previously sieved to obtain a particle size of 0.1–1.0 cm in diameter and 1.0–4.0 cm in length. To assess the potential stability of biochar, the fixed-carbon content (determined from the proximate analysis) and the atomic H:C and O:C ratios (calculated from the elemental analysis) have been taken as response variables. On the other hand, the potential phytotoxicity of produced biochars has been evaluated by three different tests, which have been based on previous studies [3,4], and using three different seed families (barley, lettuce and watercress). The germination index and radicle length have been selected as response variables. Furthermore, the potential of biochar as carrier for mycorrhizal communities has been measured as follows: a mixture of biochar and mycorrhizal inoculum was used as substrate on which barley seeds were planted in triplicate; the generated biomass after two months of growing as well as the mycorrhizal percentage of the roots have been taken as response variables. Experimental trials are almost finished and the results from the statistical analyses will be summarized and presented during the course of the conference. References [1] Brassard, P.; Godbout, S.; Raghavan, V. Biosyst. Eng. 2017, 161, 80–92. [2] Manyà, J. J.; Azuara, M.; Manso, J. A. Biomass Bioenergy 2018, 117, 115–123. [3] Liang, C.; Gascó, G.; Fu, S.; Méndez, A.; Paz-Ferreiro, J. Soil Tillage Res. 2016, 164, 3–10. [4] Buss, W.; Masek, O.; Graham, M.; Wüst, D. J. Environ. Manage. 2015, 156, 150–15
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