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The Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system is a typical system in tungsten extractive metallurgy used in the preparation and purification of ammonium tungstate solution. To determine an appropriate solution composition to optimize these processes, a thermodynamic model combined with the Pitzer activity equations was developed. This model allowed us to predict the dependence of the equilibrium WO3 concentration on the compositions of the solution in the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system. Thermodynamic analyses clarified the stable regions of CaCO3 and CaWO4 in the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system and indicated that increasing both the total NH3 and total CO2 concentrations is beneficial for increasing the equilibrium WO3 concentration. The experimental results confirm that the thermodynamic model offers a means of predicting the equilibrium concentrations of species in the system. Furthermore, the equilibrium WO3 concentrations of the solution of the Ca2+-(NH4)2CO3-(NH4)2WO4-NH3-H2O system at 298.15 K have been predicted at different total CO2 concentrations, as well as different total NH3 to total CO2 concentration ratios. Thus, the findings of this study will not only help determine the appropriate composition of the leaching system for preparing ammonium tungstate solutions, but also provide a reference for purifying ammonium tungstate solutions.

The accurate phenotyping of the external quality attributes of potato tubers is important in potato breeding. Currently, the assessment of potato tuber shape, together with eye density and depth, are based on subjective naked eye visual evaluation. However, such a manual visual assessment makes it very difficult to reliably phenotype these and other important, more complicated, geometrical traits, such as shape uniformity. In this study, a 3D image analysis method has been developed for counting potato eyes and estimating eye depth based on an evaluation of the curvature of an acquired 3D point cloud. Six shape uniformity-related traits, together with their shape indices (SI), were measured for six potato varieties. These were collected from three field experiments designed initially to study the effects of variation in nitrogen (N), potassium (K) and compound fertilisers along with tuber mass, on all investigated external traits. We demonstrate that a 3D image analysis technique can estimate the number of potato eyes and their depth with a high degree of accuracy. In addition, three shape uniformity traits were identified as offering a better power discrimination between varieties. The preliminary experiment found potato tuber mass to significantly affect both the shape uniformity and eye count, while fertiliser treatments showed no effect on all traits except SI. However, further investigation with a larger sample size is required for confirmation.

In (NH4)2CO3 solution, leaching Ca3WO6-bearing product converted from tungsten concentrate can directly obtain ammonium tungstate solution, and thus eliminates high-salinity wastewater discharge in ammonium paratungstate manufacture. Possible reactions of Ca3WO6 leaching in aqueous ammoniacal ammonium carbonate solution under atmospheric pressure were investigated thermodynamically and experimentally. The results show that tungsten in Ca3WO6 can be efficiently leached out by forming CaCO3(s) and (NH4)2WO4 (aq) in aqueous ammoniacal ammonium carbonate solution, while raising ratio of total ammonia to total carbon in solution and forming calcite are beneficial to increase the WO3 leaching ratio. Whereas the secondary reactions of Ca3WO6 with H2O and/or Ca (OH)2/CaCO3 with (NH4)2WO4 may occur and thus CaWO4 forms in the leaching, decreasing WO3 leaching ratio especially in concentrated (NH4)2WO4 solution and in case of forming vaterite. In addition, a three-layer cover was observed on the unreacted Ca3WO6 and hinders the leaching process. Through simultaneous grinding and leaching, both high WO3 leaching ratio and high WO3 concentration leachate can be achieved by increasing ratio of total ammonia to total carbon in NH3-(NH4)2WO4- (NH4)2CO3-H2O system. These results are helpful to optimize the leaching process of the converted product with Ca3WO6 by roasting tungsten-containing materials.

Apple scab is one of the most economically important diseases of apples worldwide. The disease is caused by the haploid ascomycete Venturia inaequalis. Growing apples in cultivar mixtures may reduce disease severity. To determine how the pathogen population structure is affected by host mixtures we studied 24 V. inaequalis isolates sampled from three different apple cultivars (“Bramley”, “Cox” and “Worcester”) growing in a mixed orchard approximately 50 years old. The isolates were aligned against a reference genome and single nucleotide polymorphisms (SNPs) were called between the isolates. The populations isolated from Bramley and Worcester were distinct, while Cox isolates were an admixture. This supports previous tests of the ability of isolates to cross-infect hosts, and molecular comparisons using simple sequence repeats (SSRs). Genotype specific allele (GSA) loci were not distributed randomly across contigs in proportion to contig length, but were clustered. Clustered GSA were observed in almost all contigs. This indicates population differentiation across the whole genome, presumably due to lack of crossing-over events between Bramley and Worcester isolates. This lack is probably due to physical separation effects: sexual mating is more likely to take place and succeed between isolates from lesions on the same leaf than from contact between independently infected leaves in leaf litter on the orchard floor. This would especially be the case if sexual reproduction is initiated before leaf-fall.

2D semiconductors are one of the most promising materials for next-generation electronics. Realizing continuous 2D monolayer semiconductors with single-crystalline structure at the wafer scale is still a challenge. We developed an epitaxial phase conversion (EPC) process to meet these requirements. The EPC process is a two-step process, where the sulfurization process was carried out on pre-deposited Mo-containing films. Traditionally, two-step processes for 2D MoS2 and other chalcogenides have suffered low-quality film and non-discontinuity at monolayer thickness. The reason was regarded as the low lattice quality of precursor film. The EPC process solves these problems by carefully preparing the precursor film and carefully controlling the sulfurization process. The precursor film in the EPC process is epitaxial MoO2 grown on 2″ diameter sapphire substrate by pulsed laser deposition. This epitaxial precursor contains significantly fewer defects compared to amorphous precursor films. Thus fewer defects are inherited by the EPC MoS2 film. Therefore, EPC MoS2 film quality is much better. The EPC prepared monolayer MoS2 devices to show field-effect mobility between 10 ~ 30 cm2·V-1s-1, which is the best among the two-step process. We also developed a CLAP method further to reduce the defects in the precursor oxide film; thus, in-plane texture in the thicker MoS2 film was eliminated, and a single-crystalline structure was obtained in the wafer-scale MoS2 films. The potentially feasible technique to further improve the 2D film quality is pointed out for our next research plan. Meanwhile, the epitaxial phase conversion process was proposed to be as a universal growth method. Last but not least, we demonstrate several potential applications of the wafer-scale single-crystalline MoS2 film we developed, such as logic circuits, flexible electronics, and seeding layer of van der Waal or remote epitaxial growth.