Variation in growth of peanut plants under drought stress condition and in combination with paclobutrazol and ABA

            Economically important oilseed crop peanut (Arachis hypogaea L. TVM-2) belonging to the family Fabaceae was selected for the present investigation. Field experiments were conducted to identify the variation under drought stress, paclobutrazol, and abscisic acid, and their combination on the growth of peanut plants. Drought stress decreased the morphological parameters like root length, stem length, total leaf area, fresh and dry weight on 40, 60 and 80 days after sowing (DAS) when compared to control. The paclobutrazol (PBZ) and abscisic acid (ABA) treatment to the drought stressed plants increased all the parameters when compared to drought stressed plants. PBZ treatment increased the root length when compared to control, while decreased the stem length and leaf area. ABA treated plants decreased root length, while increasing the stem length and leaf area when compared to control. Fresh and dry weight decreased in drought stressed plants when compared to control. PBZ and ABA to the drought stressed plants increased the fresh and dry weight. PBZ and ABA treatments decreased the fresh and dry weight when compared in the unstressed plants.

The effects of external surface barriers on diffusion and reaction in zeolite catalysts

Zeolites are attractive heterogeneous catalysts due to their crystalline structure, high surface area and thermal stability. However, conventional zeolites display diffusion limitations in many relevant catalytic processes. The slow diffusion rate through the extended network of micropores leads to low catalyst utilization and can, furthermore, lead to reduced selectivity and catalyst lifetime [1]. One nature-inspired approach to decrease diffusion limitations is to use hierarchically structured porous materials with an optimized network of broad and narrow pores. Observations in nature can help to provide a mechanistic basis to design the optimal pore network, since the architecture of nature is dominated by hierarchical structures. Hierarchical transport networks are indeed common in many natural systems, such as the respiratory and circulatory systems, as well as in leaves. At large length scales transport is dominated by convective flow, while at smaller length scales transport is dominated by diffusion [2]. Thus, the incorporation of hierarchical porosity can enhance the diffusion and reduce or even eliminate diffusion limitations in zeolite catalysts [3]. In addition to enhanced catalyst utilization, increasing the external surface area and maximizing the rate of intracrystalline diffusion could also lead to improved catalyst life times. Nevertheless, recent experimental and computational work suggests that external surface barriers in zeolite-based, hierarchical catalysts might play a significant role in affecting overall transport and reaction rates in such catalysts [4]. Rao et al. [5] demonstrated the existence and impact of surface barriers on the alkylation of benzene with ethylene by comparing reactor simulations with experimental results. In recent work in our group, ZSM-5 zeolites with similar bulk properties were prepared with different external surface properties, using different synthesis methods and conditions. The synthesized materials were studied extensively using different characterization techniques to determine their chemical, structural and textural properties. This set of catalysts was then used for appropriate catalytic experiments to investigate the impact of surface barriers on the catalytic properties of zeolites. This knowledge will be important to understand how surface barriers can be either avoided or exploited. References [1] M. Hartmann, A.G. Machoke, W. Schwieger: Catalytic test reactions for the evaluation of hierarchical zeolites. Chemical Society Reviews 45, 3313-3330 (2016). [2] P. Trogadas, M. Nigra, M. O. Coppens: Nature-inspired optimization of hierarchical porous media for catalytic and separation processes. New Journal of Chemistry 40, 4016-4026 (2016). [3] D. Mehlhorn, R. Valiullin, J. Kärger, K. Cho, R. Ryoo: Exploring the hierarchy of transport phenomena in hierarchical pore systems by NMR diffusion measurement. Microporous and Mesoporous Materials 164, 273-279 (2012). [4] G. Ye, Y. Sun, Z. Guo, K. Zhu, H. Liu, X. Zhou, M. O. Coppens: Effects of zeolite particle size and internal grain boundaries on Pt/Beta catalyzed isomerization of n-pentane. Journal of Catalysis 360, 152-159 (2018). [5] S. M. Rao, E. Saraçi, R. Gläser, M. O. Coppens: Surface barriers as dominant mechanism to transport limitations in hierarchically structured catalysts – Application to the zeolite-catalyzed alkylation of benzene with ethylene. Chemical Engineering Journal 329, 45-55 (2017)

On the synthesis and performance of hierarchical nanoporous TS-1 catalysts

Hierarchical TS-1 zeolite was successfully prepared using chitosan as a sacrificial template. The X-ray diffraction showed that the presence of chitosan with the synthesis precursor had no deleterious effect on the crystallinity and phase purity of this zeolite. X-ray absorption spectroscopy at the Ti K-edge, FTIR and Raman spectroscopies revealed the titanium ions in the zeolite structure have predominantly tetrahedral coordination. However, it appears that the higher chitosan content in the synthesis gel imparted some hydrophilic character to the TS-1 system. Furthermore, the technique adopted for the preparation of the synthesis gel – e.g partially dried or fully dried – appears to affect the amount of framework titanium in the zeolite structure. The calcined form of the chitosan templated TS-1 zeolites exhibited higher cyclohexene conversion compared to the TS-1 material synthesised without this template, but these catalysts showed lower selectivity for cyclohexene epoxide

VO₂/ZnO bilayer films with enhanced thermochromic property and durability for smart windows

VO_{2} films are widely considered as one of the most suitable material to act as smart windows. Although this system is able to function, the durability of the film has been an issue as the surface of the films may oxidize by converting V^{4+} to V^{5+}. To overcome this problem, attempt is made to coat the VO_{2} film with ZnO, which can assist by creating a resistance layer to prevent further oxidation of VO_{2}. Here, VO_{2}/ZnO bilayer film was prepared by a facile method comprised of spin-coating and dip-coating process and shows excellent durability, and in particular. the solar modulation efficiency (△T_{sol}) maintaining ca 89.9% (from 17.8% to 16.0%) after 300 days in a humid environment, however, the △T_{sol} of pure VO_{2} film is decreased from 11.8% to 4.1%. Also, the VO2/ZnO bilayer exhibits an enhanced thermochromic property of visible transmittance (T_{lum} = 55.7 ± 2.1%) and △T_{sol} (17.1 ± 1.4%) which is 1.49 times higher than that of pure VO2 film (△T_{sol} = 11.5 ± 0.4%). The enhancement in the thermochromic performance and durability is probably attributed to the anti-reflection and protection of ZnO layer. Therefore, this work can provide an effective way to optimize thermochromic property for practical application of VO_{2}-based smart windows

Facile Solution Process of VO2 Film with Mesh Morphology for Enhanced Thermochromic Performance

The fabrication and applications of VO2 film continue to be of considerable interest due to their good thermochromic performance for smart windows. However, low visible transmittance (Tlum) and solar modulation efficiency (∆Tsol) impede the application of VO2 film, and they are difficult to improve simultaneously. Here, a facile zinc solution process was employed to control the surface structure of dense VO2 film and the processed VO2 film showed enhanced visible transmittance and solar modulation efficiency, which were increased by 7.5% and 9.5%, respectively, compared with unprocessed VO2 film. This process facilitated the growth of layered basic zinc acetate (LBZA) nanosheets to form mesh morphology on the surface of VO2 film, where LBZA nanosheets enhance the visible transmittance as an anti-reflection film. The mesh morphology also strengthened the solar modulation efficiency with small caves between nanosheets by multiplying the times of reflection. By increasing the zinc concentration from 0.05 mol/L to 0.20 mol/L, there were more LBZA nanosheets on the surface of the VO2 film, leading to an increase in the solar/near-infrared modulation efficiency. Therefore, this work revealed the relationship between the solution process, surface structure, and optical properties, and thus can provide a new method to prepare VO2 composite film with desirable performance for applications in smart windows

Effects of the synthetic condition on the stability, particle size and redox chemistry of nanoporous CoAlPO-34

This study focuses on the effect of the synthetic conditions on the stability, particle size, redox chemistry of cobalt into the framework of CoAlPO-34. It seems that the most sufficient pH for the substitution of Co into the framework of CoAlPO-34 was pH around 7.5 when the as-synthesized bifunctional catalyst has the best redox property. The pH of the initial gel has strong effect on the particle size of CoAlPO-34. The substitution of cobalt and redox chemistry were determined by: EXAFS combined with XRD, XANES, IR. Stability of the nanoporous catalyst studied by in situ XRD were also reported

Towards understanding mesopore formation in zeolite Y crystals using alkaline additives via in situ small-angle X-ray scattering

The formation of micro/mesoporous zeolites by treating zeolite crystals with alkaline hydroxides has received a lot of interest, but fundamental understanding is still lacking. Here, we study the reactivity of a crystalline zeolitic material with various alkaline hydroxides, to close this knowledge gap. The use of ex situ and in situ small-angle X-ray scattering has allowed us to determine the reactivity of faujasite (FAU) type zeolite Y at different pH and Si/Al ratio (SAR), with a variety of different organic ammonium hydroxides. Supplemented with ex situ XRD and BET isotherm measurements, we show that the pH of the starting mixture and SAR of the zeolite significantly influence the stability of the microporous structure and the extent of formation of mesoporous material

Phase control during the synthesis of nickel sulfide nanoparticles from dithiocarbamate precursors

Square-planar nickel bis(dithiocarbamate) complexes, [Ni(S2CNR2)2], have been prepared and utilised as single source precursors to nanoparticulate nickel sulfides. While they are stable in the solid-state to around 300 °C, heating in oleylamine at 230 °C, 5 mM solutions afford pure α-NiS, where the outcome is independent of the substituents. DFT calculations show an electronic effect rather than steric hindrance influences the resulting particle size. Decomposition of the iso-butyl derivative, [Ni(S2CNiBu2)2], has been studied in detail. There is a temperature-dependence of the phase of the nickel sulfide formed. At low temperatures (150 °C), pure α-NiS is formed. Upon raising the temperature, increasing amounts of β-NiS are produced and at 280 °C this is formed in pure form. A range of concentrations (from 5–50 mM) was also investigated at 180 °C and while in all cases pure α-NiS was formed, particle sizes varied significantly. Thus at low concentrations average particle sizes were ca. 100 nm, but at higher concentrations they increased to ca. 150 nm. The addition of two equivalents of tetra-iso-butyl thiuram disulfide, (iBu2NCS2)2, to the decomposition mixture was found to influence the material formed. At 230 °C and above, α-NiS was generated, in contrast to the results found without added thiuram disulfide, suggesting that addition of (iBu2NCS2)2 stabilises the metastable α-NiS phase. At low temperatures (150–180 °C) and concentrations (5 mM), mixtures of α-NiS and Ni3S4, result. A growing proportion of Ni3S4 is noted upon increasing precursor concentration to 10 mM. At 20 mM a metastable phase of nickel sulfide, NiS2 is formed and as the concentration is increased, α-NiS appears alongside NiS2. Reasons for these variations are discussed

Following Cu Microstructure Evolution in CuZnO/Al_{2}O_{3}(−Cs) Catalysts During Activation in H_{2} using in situ XRD and XRD-CT

Understanding how the microstructure of the active Cu0 component in the commercially applicable Cu/ZnO/Al_{2}O_{3}(−Cs_{2}O) low-temperature water-gas shift catalyst evolves under various H_{2} partial pressures in the presence/absence of a Cs promoter during thermal activation has been investigated. Time-resolved XRD and spatially-resolved XRD-CT data were measured as a function of H_{2} concentration along a packed bed reactor to elucidate the importance of the zincite support and the effect of the promoter on Cu sintering mechanisms, dislocation character and stacking fault probability. The rate of Cu reduction showed a dependency on [Cs], [H_{2}] and bed height; lower [Cs] and higher [H_{2}] led to a greater rate of metallic copper nanoparticle formation. A deeper analysis of the XRD line profiles allowed for determining a greater edge character to the dislocations and subsequent stacking fault probability was also observed to depend on higher [H_{2}], Cu^{0} (and ZnO) crystallite sizes, increased [ZnO] (30 wt.%, sCZA) and lower temperature. The intrinsic activity of Cu/ZnO/Al_{2}O_{3} methanol synthesis catalysts has been intimately linked to the anisotropic behaviour of copper, and thus the presence of lattice defects; to the best knowledge of the authors, this study is the first instance in which this type of analysis has been applied to LT-WGS catalysts