Generalized Gruneisen parameters of elastic waves and the low-temperature thermal expansion of alumina from its third-order elastic-constant data

The generalized Gruneisen parameters (GP's) of elastic waves propagating in different directions in aluminum oxide are calculated from the measured second- and third-order elastic constants. These GP's in alumina are found to have small but positive values. The Brugger gammas are evaluated and the low-temperature limit of the Gruneisen gamma is calculated using the procedure of Ramji Rao and Srinivasan. _L has the value 1.37, indicating that the thermal expansion of alumina is positive down to 0 K.     

Adsorption of streptomycin on ion exchange resins: Equilibrium and kinetic studies

Equilibrium and kinetic studies of streptomycin adsorption from aqueous solutions of streptomycin sulphate were carried out using four weakly acidic ion exchange resins: Indion 236 [Ion Exchange (India) Ltd], Amberlite IRC-50 (Rohm and Haas Co, USA), KB-2 and KB4-P2 (both Russian resins), initially in the sodium form. The maximum amounts of streptomycin taken up by the exchangers were about 1640, 1560, 2050 1400 mg g^?1 dry resin (sodium form), respectively. The rate of adsorption of the antibiotic was highest with the ion-exchanger KB-2, and lowest with KB4-P2. The initial diffusivity values calculated for the four exchangers at a temperature of 9°C were 2.87 × 10^?8, 1.87 × 10^?8, 3.42 × 10^?8 and 0.468 × 10^?8 cm² s^?1, respectively.     

Reaction Densification of α'-SiAlON: 1, Wetting Behavior and Acid-Base Reactions

Phase development during reaction hot pressing of α-Si₃N₄, AlN, Al₂O₃, and M₂O_Z powder mixtures (M = Li, Mg, Ca, Y, Nd, Sm, Gd, Dy, Er, and Yb) forming α'-SiAlON has been studied. The wetting behavior of the ternary eutectic melt of M₂O_z-Al₂O₃-SiO₂ was found to control the reaction sequence during hot pressing. Li, Ca, Mg, Nd, Sm, and Gd were found to preferentially wet and react with Si₃N₄ first, whereas Dy, Er, and Yb preferentially wetted and reacted with AlN first. The intermediate phases are Si rich in the former and Al rich in the latter case. Pearson's principle of acid-base theory, which predicts decreasing basicity of oxides of Li, Ca, Mg, Nd, Gd, Sm, Dy, Er, and Yb and decreasing acidity of oxides of Si and Al, is used to understand these reactions.     

A systematic method to synthesize all dividing wall columns for n‐component separation: Part II

We present a simple rule that, for the first time, enables exhaustive enumeration of dividing wall columns (DWCs) corresponding to any given thermally coupled distillation column‐configuration. With the successive application of our rule, every partition in a DWC can be extended all the way to the top and/or to the bottom of a column without losing thermodynamic equivalence to the original thermally coupled configuration. This leads to easy‐to‐operate DWCs with possible control/regulation of each and every vapor split by external means. As a result, we conclude that any given DWC can be transformed into a thermodynamically equivalent form that is easy‐to‐operate, and hence, there always exists at least one easy‐to‐operate DWC for any given thermally coupled distillation. Our method of enumerating and identifying easy‐to‐operate DWCs for an attractive thermally coupled configuration will contribute toward process intensification by providing ways to implement efficient and low‐cost multicomponent distillations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 660–672, 2018     

Systematic Power Factor Enhancement in n‐Type NiETT/PVDF Composite Films

Nickel ethenetetrathiolate (NiETT) coordination polymers are shown to exhibit high thermoelectric performance as pressed pellets. Because the material is insoluble, films are formed by fabricating a composite of the material in an inert polymer matrix, a process that adversely impacts thermoelectric properties. To date, a reliable and reproducible synthesis has not been reported, which was the motivation for a systematic study of the substeps involved to understand the reaction mechanism. The results of these studies yield optimized reaction conditions for high performance n‐type films, which are derived from empirical studies and material characterization. Herein, a reaction procedure is presented that gives reproducible properties when preparing batches in the 0.5–15 g range. The identity of the counterion, nickel equivalency, and oxidation extent are investigated, which provide insight into the synthetic reaction mechanism and the ligand‐centered oxidation process in these polymers. Optimized materials based on Na[NiETT] exhibit one of the highest n‐type thermoelectric performance for solution‐processed films reported to date, with power factors of 23 µW (m K)^?2 (due to conductivities approaching 50 S cm^?1) while maintaining their stability in ambient conditions.     

Simultaneous Enhancement in Electrical Conductivity and Thermopower of n‐Type NiETT/PVDF Composite Films by Annealing

Nickel ethenetetrathiolate (NiETT) polymers are promising n‐type thermoelectric (TE) materials, but their insolubility requires the use of an inert polymer matrix to form films, which is detrimental to the TE performance. In this work, the use of thermal annealing as a post‐treatment process simultaneously enhances the electrical conductivity from 6 ± 2 to 23 ± 3 S cm^?1 and thermopower from ?28 ± 3 to ?74 ± 4 µV K^?1 for NiETT/PVDF composite films. Spectroscopic characterization reveals that the underlying mechanism involves removal of residual solvent and volatile impurities (carbonyl sulfide and water) in the NiETT polymer backbone. Additionally, microscopic characterization reveals morphological changes caused by a densification of the film that improves chain packing. These effects result in a 25 × improvement in power factor from 0.5 to 12.5 µW m^?1 K^?2 for NiETT/PVDF films and provide insight into the composition of these coordination polymers that maintain their stability under ambient conditions.     

A Millimetre-Wave Cuboid Solid Immersion Lens with Intensity-Enhanced Amplitude Mask Apodization

Photonic jet is a narrow, highly intensive, weak-diverging beam propagating into a background medium and can be produced by a cuboid solid immersion lens (SIL) in both transmission and reflection modes. Amplitude mask apodization is an optical method to further improve the spatial resolution of a SIL imaging system via reduction of waist size of photonic jet, but always leading to intensity loss due to central masking of the incoming plane wave. In this letter, we report a particularly sized millimetre-wave cuboid SIL with the intensity-enhanced amplitude mask apodization for the first time. It is able to simultaneously deliver extra intensity enhancement and waist narrowing to the produced photonic jet. Both numerical simulation and experimental verification of the intensity-enhanced apodization effect are demonstrated using a copper-masked Teflon cuboid SIL with 22-mm side length under radiation of a plane wave with 8-mm wavelength. Peak intensity enhancement and the lateral resolution of the optical system increase by about 36.0% and 36.4% in this approach, respectively.     

A novel local octa-pattern feature descriptor for image retrieval

The local tetra patterns (LTrPs) gives four-directional information and ignores the diagonal pixel information, thereby affecting the retrieved image efficiency. In the present work, a novel retrieval approach has been proposed using local octa-patterns (LOcPs) for content-based image indexing and retrieval. The proposed approach encodes the center pixel directional information with its eight adjacent neighbors, from the directions that are computed using the first-order derivatives. Also the nth-order LOcP is computed using \((n-1)\)th-order local direction variations. In addition, the performance of the developed method by combining it with the Gabor transform has been analyzed. The performance of the proposed technique has been compared to existing techniques like LBP, LTP, LDP, and LTrP on Corel-1000 database (DB1) and Describable Textures Dataset (DB2). The performance observed shows that the developed method improves the retrieval parameters from 75.9%/77.13% to 79.4%/81.5% in the form of average precision on DB1/DB2 databases.     

Effect of phosphate rock sources on biological nitrogen fixation by soybean

Very little information is available concerning the effect of phosphate rock (PR) sources on biological nitrogen fixation (BNF) in legume crops. In a greenhouse study, the¹⁵N isotopic dilution technique was used to compare the effectiveness of three sources of PR (Hahotoe rock, Togo; Tilemsi rock, Mali; and Sechura rock, Peru) with that of triple superphosphate (TSP) in increasing soybean seed yield and the amounts of N fixed by the soybean crop. The acid Hartsells slit loam was limed to pH 5.2 and incubated with 8.5 mg N kg^–1 as K¹⁵NO₃ and sucrose for 2 months prior to planting. Then fertilizer P was incorporated into the soil at 12.5, 25, 50, and 100 mg P kg^–1 rates.The relative agronomic effectiveness (RAE) of the three PRs with respect to TSP (RAE = 100%) in terms of increasing seed yield was Hahotoe rock = 6.0%, Tilemsi rock = 45.9%, and Sechura rock = 75.2%; this trend followed the same trend as PR reactivity, i.e., Sechura rock > Tilemsi rock > Hahotoe rock. BNF was affected significantly by all the P treatments. Of the total N derived from the three N sources (atmosphere, N_dfa; fertilizer K¹⁵NO₃, N_dff; and soil, N_dfs), N_dfa was highest with TSP and lowest with Hahotoe rock, whereas the reverse was found with N_dfs. Among various plant parts, more N_dfa was translocated and stored in seeds than in stems + leaves and roots. The RAE values of the three PRs with respect to TSP (RAE = 100%) in terms of influencing the amount of BNF were Hahotoe rock = 3.0%, Tilemsi rock = 43.4%, and Sechura rock = 71.2%. A linear relationship was found between the amount of BNF by the whole soybean plant and the soybean seed yield.