1,073 research outputs found

    Activated biochars as sustainable and effective supports for hydrogenations

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    Activated biochars were obtained from pyrolysis and CO2-physical activation of four different biomasses including tannery shaving waste (T), vine wood waste (W), barley waste (B) and Sargassum, brown macroalgae of Venice lagoon (A). The potential of obtained carbonaceous materials as the supports of Ni,Al catalysts was investigated in levulinic acid (LA) conversion to Ī³-valerolactone (GVL) as a model hydrogenation reaction. Al-containing species as the Lewis acid sites for the dehydration step were incorporated to the supports using wet impregnation or precipitation. Ni as a hydrogenation active phase was added to the supports via wet impregnation. Biochar-based supports and catalysts were characterized by AAS, elemental analysis, FTIR, N2 physisorption, XRD, SEM, EDS, TEM, He-TPD, NH3-TPD and TPR techniques. The catalysts were tested for LA hydrogenation to GVL in a batch system and aqueous medium. The results showed that Ni supported on activated biochar was not active due to a lack of Lewis acid sites for dehydration. Precipitated Al-containing species on the biochar-based supports demonstrated a better catalytic performance in the reaction compared to impregnated one because of different interactions with the support and Ni species. Among different supports, the activated biochars obtained from T and W acted as the best ones. A higher catalytic efficiency was strongly influenced by the chemical (aromaticity and stability, presence of N,O-doped and functional groups), textural (the porous texture and surface area), and morphological (higher dispersion of active phases) properties of activated biochars obtained from different biomasses with different natures

    Fractionation comparison of Persian Gulf jellyfish nematocyst venom by two methods of chromatography

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    In this paper, the nematocyst venom of the crambionella orsini jellyfish was fractionated by sizeexclusion and anion-exchange chromatography. Crambionella orsini is a jellyfish common to the Persian Gulf. The results of the mentioned methods have been investigated. The crambionella orsiniā€™s venom has a hemolytic effect, which is similar to the other species. After the extraction of the nematocyst venom, the crude venom was partially purified using sephadex G-200 gel filtration and DEAE anion exchange chromatography. Protein elution was monitored by UV detection at 28 0nm. To determine the hemolytic fraction, every fraction was injected to 3 mice via their tail vein. Finally, all the data from both chromatography methods were compared. The gel filtrations second fraction and the first and second fractions of the anion exchange chromatography showed hemolytic activity. Determining an appropriate method for the purification of this venom can help find a comprehensive method for other marine venoms, especially jellyfish venoms, and may eventually help find specific antidotes for the stings of jellyfish of these species

    Extraction and neutralization nematocyst venom of Crambionella orsini jellyfish [whit] using of chelating Na-EDTA

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    Jellyfish is one of the poisonous animals that causing human poisoning. Found a variety of jellyfish in the Persian Gulf. Although these species can't Cause of quick death in humans but they have harmful effects on human health system and have Following are the side effects. In this study extracted Crambionella Orsini Jellyfish Venom According to Bloom method and was obtained its Concentration by Biuret method and Calculated LD50 by Jung and Choi method. According to Venom concentration and its LD50 was determined that Cause of death mice 0.5 ml of venom. The use of Na-EDTA for neutralizing venom. This Chelate Was injected in two ways to mice that in both methods, Prevented death. Na-EDTA is dedicated Chelate for Calcium excretion from body that According to nuclear calcium's venom is able to separated that from Venom structure and neutralize venom

    Effects of different by catch reduction devices (BRDs) in shrimp trawlers in the Persian Gulf

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    The effect of different bycatch reduction devices in decreasing bycatch of commercial fish species with the length of less than LM50 (the length from which, 50% of them are matured) in shrimp trawlers were examined. The experiments were conducted in Persian Gulf (Bushehr and Hormuzgan provinces) during the shrimp season, years 2000-2001. In this study four types of bycatch reduction devices (Grid, Nafted, Fish eye and Square mesh window) were used. Double rig trawl was used, one of them as an experimental trawl and the other as the control. Different treatments like one device or two devices were installed on experimental shrimp net. After hauling the trawl, frquency of different commercial species with length less than LM50 was determined in both nets, and the results were tested with Paired Willcoxon test. The results have shown that although all the devices have a reductional effect on bycatch of the young and juveniles of commercial species, but the amount of reduction with setting Nafted and Grid, either single or combined with another BRD was significantly higher than the control one (P ā‰¤ 0/05). The amount of by catch reduction devices with different treatment (different devices either single or paired) according to the season of the experiment were also tested with Kruskal- Wallis test, which shows significant differences (Pā‰¤0.05) between the frquency of young and juvenile individuals of some species during different experimental seasons. According to this study, by using Nafted and Grid devices in the trawl nets of all shrimp vessels during its season, about 400 to 500 thousand of juveniles and young individuals can escape from the nets

    The effect of changes in temperature on the toxicity of jellyfish, Crambionella orsini

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    The aim of this study was to evaluate the effect of temperature changes to reduce toxicity of jellyfish Crambionellaorsini venom. Venom extraction was done according to Bloom method. Sonication was used to break the wall of nematocysts capsule and then the resulting solution was centrifuged. To evaluate the effect of temperature on the venom, it was heated at different temperatures and then injected into sori mice. After catching jellyfish, Crambionellaorsini from Arvand stream estuary edges of umbrellas and tentacles of jellyfish were separated and kept in water LD_50 of toxins were calculated by Jung and Choi method and statistical analysis to obtain minimal lethal dose of poison done by Excel 2007. The results showed that the venom of jellyfish Crambionellaorsini, like venom of other animals is, based on a protein and that is sensitive to heat. This venom is disabled and lose their structure at 48 Ā°C and its minimum lethal dose is 0.5 ml

    Microstructural evolution under low shear rates during Rheo processing of LM25 alloy

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    Ā© ASM InternationalMicrostructural features of LM25 alloy processed by two different routes: (1) conventional casting, and(2)shear casting based on inclined heated surface are studied. The microstructures of the primary phase for the shear-cast samples show rosette or ellipsoidal morphologies. Heat transfer of contacting melt with the inclined tube surface and shear stress exerted on the layers of the melt as result of gravitational force are crucial parameters for the microstructural evolution. Compared to those produced by conventional casting, shear-cast samples have a much improved tensile strength and ductility due to globular microstructure

    A new approach to calculate the gluon polarization

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    We derive the Leading-Order master equation to extract the polarized gluon distribution G(x;Q^2) = x \deltag(x;Q^2) from polarized proton structure function, g1p(x;Q^2). By using a Laplace-transform technique, we solve the master equation and derive the polarized gluon distribution inside the proton. The test of accuracy which are based on our calculations with two different methods confirms that we achieve to the correct solution for the polarized gluon distribution. We show that accurate experimental knowledge of g1p(x;Q^2) in a region of Bjorken x and Q^2, is all that is needed to determine the polarized gluon distribution in that region. Therefore, to determine the gluon polarization \deltag /g,we only need to have accurate experimental data on un-polarized and polarized structure functions (F2p (x;Q^2) and g1p(x;Q^2)).Comment: 12 pages, 5 figure

    A general algorithm for manipulating non-linear and linear entanglement witnesses by using exact convex optimization

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    A generic algorithm is developed to reduce the problem of obtaining linear and nonlinear entanglement witnesses of a given quantum system, to convex optimization problem. This approach is completely general and can be applied for the entanglement detection of any N-partite quantum system. For this purpose, a map from convex space of separable density matrices to a convex region called feasible region is defined, where by using exact convex optimization method, the linear entanglement witnesses can be obtained from polygonal shape feasible regions, while for curved shape feasible regions, envelope of the family of linear entanglement witnesses can be considered as nonlinear entanglement witnesses. This method proposes a new methodological framework within which most of previous EWs can be studied. To conclude and in order to demonstrate the capability of the proposed approach, besides providing some nonlinear witnesses for entanglement detection of density matrices in unextendible product bases, W-states, and GHZ with W-states, some further examples of three qubits systems and their classification and entanglement detection are included. Also it is explained how one can manipulate most of the non-decomposable linear and nonlinear three qubits entanglement witnesses appearing in some of the papers published by us and other authors, by the method proposed in this paper. Keywords: non-linear and linear entanglement witnesses, convex optimization. PACS number(s): 03.67.Mn, 03.65.UdComment: 37 page

    One-Pot Transformation of Citronellal to Menthol Over H-Beta Zeolite Supported Ni Catalyst: Effect of Catalyst Support Acidity and Ni Loading

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    Citronellal was converted to menthol in a one-pot approach using H-Beta zeolite-based Ni catalyst in a batch reactor at 80 Ā°C, under 20 bar of total pressure. The effects of H-Beta acidity (H-Beta-25 with the molar ratio SiO2/Al2O3 = 25 and H-Beta-300 with SiO2/Al2O3 = 300) and Ni loading (5, 10 and 15 wt %) on the catalytic performance were investigated. Ni was impregnated on H-Beta support using the evaporation-impregnation method. The physico-chemical properties of the catalysts were characterized by XRD, SEM, TEM, ICP-OES, N2 physisorption, TPR, and pyridine adsorptionā€“desorption FTIR techniques. Activity and selectivity of catalysts were strongly affected by the BrĆønsted and Lewis acid sites concentration and strength, Ni loading, its particle size and dispersion. A synergetic effect of appropriate acidity and suitable Ni loading in 15 wt.% Ni/H-Beta-25 catalyst led to the best performance giving 36% yield of menthols and 77% stereoselectivity to (Ā±)-menthol isomer at 93% citronellal conversion. Moreover, the catalyst was successfully regenerated and reused giving similar activity, selectivity and stereoselectivity to the desired (Ā±)-menthol isomer as the fresh one. Graphical Abstract: [Figure not available: see fulltext.

    Status of the tiger tooth croaker, Otolithes ruber (Schneider, 1801) and jinga shrimp, Metapenaeus affinis(H. Milne Edwards, 1837) stocks in Khouzestan coastal waters

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    Population dynamics parameters and exploitation ratio of Jinga Shrimp, Metapenaeus affinis were studied from Sep 2011 to Dec 2011 and data collected from two landing places (Hendijan and Lifee-Bosif). During the project, more than 2200 specimens of jinga shrimp were measured. The mean value of length for the male and female were calculated as 9.8Ā±0.86, 10.24Ā±1.18 and mean value of weight for the male and female was as 6.730Ā±1.64, 8.14Ā±2.90 respectively. The length-weight relation were calculated as TW=0.024TL2.24 (n=1084,R^2=0.71) for males, TW=0.011TL2.80 (n=1081,R^2= 0.81) for females also we found significant different level length-weight relation in P<0.05. The growth parameters of von Bertalanffy equation were as, L_āˆž: 14.73 and K: 1.1 and t0: -0.02. The estimated valve of total mortality, natural mortality, fishing mortality and exploitation ratio is Z: 4.35, M: 1.68, F: 2.67, E: 0.61 respectively. By using method analyses knife-edge selection, relative yield per recruitment (Y'/R) :0.014, relative biomass per recruitment, (B'/R) :0.085., Exploitation ratio maximum sustainable yield, Emax : 0.38; biological reference points for Jinga Shrimp stock was calculated. MSY and fmsy value was 600T and 46100day respectively. Result in this study showed exploitation ratio Jinga Shrimp stock is over fishing and decreases exploitation ratio proposed
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