194 research outputs found

    ZSM-5/Silicalite-1 core-shell beads as CO<sub>2</sub> adsorbents with increased hydrophobicity

    Get PDF
    Zeolites are commonly used for selective CO2 adsorption from biogas and flue gas. One of the biggest challenges for zeolites in this application is the presence of water vapour in the raw gas streams. While zeolites with low Si/Al ratio typically display high CO2 adsorption, they are hydrophilic and H2O competes for adsorption on the active sites. On the other hand, zeolites with high Si/Al ratio are hydrophobic, but display lower CO2 adsorption capacities. In order to overcome this limitation and to combine the high CO2 adsorption capacity of low Si/Al zeolites and the hydrophobicity of high Si/Al zeolites into a single material, we designed and synthesized novel core-shell zeolitic beads comprising a ZSM-5 core and a Silicalite-1 shell. Two different strategies were employed to synthesize these macroscopic core-shell beads. In both approaches, the initial step was the synthesis of binderless ZSM-5 beads with hierarchical porosity using resin beads as hard template. In the first strategy, a shell of Silicalite-1 was synthesized on the external surface of the calcined ZSM-5 beads, yielding Sil-ZSM-A core-shell beads (0.84 ± 0.12 mm). In the second strategy, the Silicalite-1 shell was synthesized without first removing the polymeric template from the ZSM-5 beads, resulting in core-shell composite beads that after calcination yielded Sil-ZSM-B core-shell beads (0.73 ± 0.14 mm). Characterization by SEM, XRD, XRF, ICP-AES and N2 physisorption indicated that both Sil-ZSM-A and Sil-ZSM-B beads displayed the desired zeolitic core-shell structure with hierarchical porosity. Both core-shell beads showed the anticipated increase in hydrophobicity. The most promising results were obtained with Sil-ZSM-A beads, which displayed a 40% decrease in H2O adsorption capacity at 20% relative humidity (RH) and a 28% decrease at max RH compared to the parent ZSM-5 beads. At the same time, their CO2 adsorption capacity (1.94 mmol/g at 1 bar) decreased only slightly compared to the parent ZSM-5 beads (2.13 mmol/g at 1 bar). These results indicate that these core-shell beads present the desired combination of the high CO2 adsorption capacity of the ZSM-5 core with the hydrophobicity of the Silicalite-1 shell. This is a promising feature for application in the adsorption of CO2 from water-containing streams.</p

    Interactions between nitrogen nutrition, canopy architecture and photosynthesis in rice, assessed using high-resolution 3D reconstruction

    Get PDF
    Increasing nitrogen use efficiency is a key target for yield improvement programs. Here we identify features of rice canopy architecture during altered N availability and link them to photosynthetic productivity. Empirical mathematical modelling, high-resolution 3-dimensional (3D) reconstruction and gas exchange measurements were employed to investigate the effect of a mild N deficiency vs. surplus N application on canopy architecture, light and photosynthesis distribution throughout development. Three contrasting rice lines: two Malaysian rice varieties (MR219 and MR253) and a high-yielding indica cultivar (IR64) were cultivated. 3D reconstruction indicated key N-dependent differences in plant architecture and canopy light distribution including changes to leaf area index (LAI), tiller number, leaf angle and modelled light extinction coefficients. Measured leaf photosynthetic capacity did not differ substantially between the high and reduced N treatments; however, modelled canopy photosynthesis rate indicated a higher carbon gain per unit leaf area for the reduced N treatment but a higher carbon gain per unit ground area for the high N treatment. This is a result of altered canopy structure leading to increased light distribution under reduced N which partially offsets the reduced LAI. Within rice, altered N availability results in the development of full photosynthetically functional leaves, but leads to altered canopy architecture, light distribution and overall productivity suggested that N availability can be fine-tuned to optimize biomass production. We propose wider use of 3D reconstruction to assess canopy architecture and productivity under differing N availabilities for a range of species

    Formulacija i evaluacija monolitnih matriksnih polimernih filmova za transdermalnu isporuku nitrendipina

    Get PDF
    The objective of the present work was to develop a suitable transdermal drug delivery system for nitrendipine. Polymeric films of nitrendipine were prepared by the film casting technique (glass ring) on mercury substrate. They were evaluated for physicochemical parameters, in vitro release and ex vivo permeation (heat separated human epidermis). Release of the drug from the films followed anomalous transport (0.5 < n < 1). Polymeric combination containing Eudragit RL 100:PVP K 30 in 4:6 ratio showed the best results. Maximum drug release and skin permeability coefficient in 48 h were 85.8 % and 0.0142 cm h-1, respectively, in formulation C3 (Eudragit RL 100: Plasdone S 630; 4:6) and 88.0 % and 0.0155 cm h-1, respectively, in formulation D3 (Eudragit RL 100: PVP K 30; 4:6). FTIR and TLC studies indicated no drug and polymer interaction.Cilj rada bio je razvoj transdermalnog sustava nitrendipina. Polimerni filmovi nitrendipina pripravljeni su metodom lijevanja (stakleni prsten) na podlozi od žive. Ispitivani su fizičkokemijski parametri, in vitro oslobađanje i ex vivo permeacija (toplinom odvojena humana epiderma). Oslobađanje lijeka iz filmova slijedilo je anomalni transport (0,5 < n < 1). Najbolji rezultati postignuti su kombinacijom polimera Eudragit RL 100 i PVP K 30 u omjeru 4:6. Maksimalno oslobađanje ljekovite tvari i najbolji koeficijent permeacije kroz kožu tijekom 48 h bio je 85,8 %, odnosno 0,0142 cm h1 za formulaciju C3 (Eudragit RL 100 : Plasdone S 630; 4:6) i 88,0 %, odnosno 0,0155 cm h1 za formulaciju D3 (Eudragit RL 100 : PVP K 30; 4:6). FTIR i TLC ukazuju na to da nema interakcije između ljekovite tvari i polimera

    Observation of multiple doubly degenerate bands in ¹⁹⁵Tl

    Get PDF
    The High-spin states in 195 Tl, populated through the 185,187 Re( 13 C, xn) fusion evaporation reaction at the beam energy of 75 MeV, were studied using the Indian National Gamma Array (INGA). More than 50 new γ transitions have been placed in the proposed level scheme which is extended up to the excitation energy of ≈ 5.6 MeV and spin =22.5ħ . Two pairs of degenerate bands based on two different quasi-particle configurations have been identified in this nucleus indicating the first observation of such bands in an odd- A nucleus in A∼190 region and signify the first evidence of multiple chiral bands in a nucleus in this region. The total Routhian surface calculations predict triaxial shapes for both the configurations and thereby, support the experimental observation. The importance of multiple neutron holes in the i13/2 orbital and the stability of shapes for these two configurations have been discussed.Financial support of Department of Science & Technology, Govt. of India for clover detectors of INGA (Grant No. IR/S2/PF-03/2003-II) is greatfully acknowledged. One of the authors (S. Bhattacharya) acknowledges with thanks the financial support received as Raja Ramanna Fellowship from the Department of Atomic Energy, Govt. of India. T.R and Md. A.A acknowledge with thanks the financial support received as research fellows from the Department of Atomic Energy (DAE), Govt. of India

    Mapping and linking supply- and demand-side measures in climate-smart agriculture. A review

    Get PDF
    Climate change and food security are two of humanity’s greatest challenges and are highly interlinked. On the one hand, climate change puts pressure on food security. On the other hand, farming significantly contributes to anthropogenic greenhouse gas emissions. This calls for climate-smart agriculture—agriculture that helps to mitigate and adapt to climate change. Climate-smart agriculture measures are diverse and include emission reductions, sink enhancements, and fossil fuel offsets for mitigation. Adaptation measures include technological advancements, adaptive farming practices, and financial management. Here, we review the potentials and trade-offs of climate-smart agricultural measures by producers and consumers. Our two main findings are as follows: (1) The benefits of measures are often site-dependent and differ according to agricultural practices (e.g., fertilizer use), environmental conditions (e.g., carbon sequestration potential), or the production and consumption of specific products (e.g., rice and meat). (2) Climate-smart agricultural measures on the supply side are likely to be insufficient or ineffective if not accompanied by changes in consumer behavior, as climate-smart agriculture will affect the supply of agricultural commodities and require changes on the demand side in response. Such linkages between demand and supply require simultaneous policy and market incentives. It, therefore, requires interdisciplinary cooperation to meet the twin challenge of climate change and food security. The link to consumer behavior is often neglected in research but regarded as an essential component of climate-smart agriculture. We argue for not solely focusing research and implementation on one-sided measures but designing good, site-specific combinations of both demand- and supply-side measures to use the potential of agriculture more effectively to mitigate and adapt to climate change
    corecore