Showcasing the optical properties of monocrystalline zinc phosphide thin films as an earth-abundant photovoltaic absorber

Zinc phosphide, Zn3P2, is a semiconductor with a high absorption coefficient in the spectral range relevant for single junction photovoltaic applications. It is made of elements abundant in the Earth’s...

Control of Common Vole (Microtus arvalis) in Alfalfa Crops Using Reduced Content of Anticoagulants

The common vole, Microtus arvalis, which is prone to cyclic overpopulation, poses a significant threat to sustainable alfalfa production by either chewing shoots periodically or gnawing and damaging roots permanently. In areas with established vole colonies, the density of alfalfa plants was shown to decrease 55.3–63.4%. Simultaneously, the number of alfalfa shoots decreased by 60.9–71.7%. These experiments were conducted in compliance with an EPPO standard method in alfalfa fields at three geographically remote sites. The experiment tested the efficacy of the most widely used acute rodenticide zinc phosphide (2%), and anticoagulants applied at significantly reduced doses of active ingredients, i.e., bromadiolone (25 ppm) and brodifacoum (25 ppm), as well as a combination of these active ingredients at a low concentration (10 + 10 ppm). Three weeks after treatment, zinc phosphide and brodifacoum achieved the highest average efficacy, at 98.5% and 92.05%, respectively, while the average efficacy of the anticoagulant combination and bromadiolone was 87.2% and 75.5%, respectively. The achieved efficacy of baits based on brodifacoum and the combination of brodifacoum and bromadiolone in controlling common voles indicates their possible utilization in the field. Baits with 25 ppm of brodifacoum and the combination of bromadiolone and brodifacoum (10 + 10 ppm) showed satisfactory results and their introduction could significantly improve pest management programs for rodent control. At the same time, the use of anticoagulant rodenticides with reduced contents of active ingredients would significantly reduce their exposure to non-target animals, especially predators and vultures. By further improving the palatability of tested baits for target rodent species, their efficacy and safety of application would be significantly improved.

Fatal Fulminant Hepatic Failure in a Case of Zinc Phosphide Poisoning: A Case Report

Rodenticide is the term given for the compounds that are used in the killing of rats. The commonest compounds that are available as rodenticides are Aluminum phosphide, Zinc Phosphide, Yellow Phosphorus and Coumarins. Due to their easy availability in the general stores, these also have been used as a source of inflicting self-harm by the patients in order to commit suicide. Most of the patients escape the poisonous side effects with a mild course, but some cases progress to a state of Acute liver failure or fulminant liver failure. Due to the broad range of symptoms that can occur with the compounds, it is important to discuss the course of progression of symptoms from mild to severe in order to understand the treatment protocols to treat the patient appropriately. Some patients progress to such a severe form of symptoms that there is an urgent indication of liver transplantation. Here we report a case of rodenticide poisoning in a young female which started off with a mild course and ultimately progressed to fulminant liver failure leading to a fatal outcome.

Acute oral toxicity of zinc phosphide: an assessment for wild house mice in Australia

BACKGROUND: The efficacy of zinc phosphide (ZnP) for broadacre control of wild house mice in Australia is being reported by growers as increasingly variable. Have mice become less sensitive over time or are they taking a sub-lethal dose and developing aversion? In this laboratory study the sensitivity of groups of wild caught and an outbred laboratory strain of mice was assessed using oral gavage of a range of ZnP concentrations. The willingness of mice to consume ZnP-coated grains was then determined. RESULTS: Each mouse group had very similar LD50 values (72 to 79 mg ZnP per kg body weight) which are significantly higher than previously reported. Time to death post-gavage ranged between 2.5 to 48 h. ZnP coated grains (50 mg ZnP per kg grain) presented in the absence of alternative food were consumed and 94 percent of wild mice died. Mice provided with alternative food and ZnP coated wheat grains (either 25 or 50 mg ZnP per kg grain) consumed toxic and non-toxic grains, and mortality was lower (33 to 55 percent). If a sublethal amount of ZnP coated grain was consumed, aversion occurred mostly in the presence of alternative food. CONCLUSIONS: The sensitivity of wild house mice to ZnP in Australia is significantly lower than previously assumed. Under laboratory conditions ZnP coated grains coated with a new higher dose (50 mg ZnP per kg grain) were readily consumed. Consumption of toxic grain occurred when alternative food was available but was decreased. It is important to assess the efficacy of the higher ZnP dose per grain under natural field conditions, especially when background food is low.

Solution Phase Syntheses of Nanoparticles and Nanowires

<p>This thesis is concerned with the preparation of metal and semiconductor nanostructures in solution, specifically bismuth and indium metal nanoparticles, gallium nitride nanoparticles, indium phosphide nanowires and zinc phosphide nanoparticles. There were two aims: firstly to study if gallium nitride nanoparticles with improved crystallinity and size distribution could be synthesized and secondly to find and develop new methods to prepare crystalline indium phosphide nanowires and zinc phosphide nanoparticles using precursors that are safe and cheap. The crystallinity, structures, morphologies and chemical compositions of the nanostructures synthesized in this thesis were studied primarily by transmission electron microscopy (TEM), powder X-ray diffraction (PXRD) and energy dispersive X-ray spectrometry (EDS). For the synthesis of gallium nitride, two approaches were taken. The first revolves around the direct metathesis reaction between gallium trichloride and lithium nitride under ambient pressure. A range of solvents with different polarities has been tested and only in highly polar solvents crystalline nanostructures were produced. These crystalline nanostructures however are not of gallium nitride. The second approach involves thermally decomposing an organometallic precursor. Organometallic compounds [Ga2(NMe2)6] (compound 1) and [(Me3C)2Ga(u-NHNHCMe3)] (compound 2) were chosen from the literature as precursors. Compound 1 was synthesized in a very small yield together with by-products. Thermal decomposition of the mixture produced no nanoparticles. A compound (compound S2) which is structurally similar to compound 2 was successfully synthesized and was subjected to thermal decomposition in ammonia to produce crystalline monodispersed nanoparticles. However, these nanoparticles could not be confidently identified as gallium nitride. The outcome from the reaction of lithium borohydride and indium trichloride was found to be strongly solvent dependent. In toluene a white precipitate was obtained. Both in isobutylamine and N,N-diethylaniline indium metal nanoparticles were produced as black solutions. Only in isobutylamine, small monodispersed indium nanoparticles can be produced. The isobutylamine method was extended to prepare bismuth metal nanoparticles. However, the bismuth nanoparticles prepared were moderately polydispersed in size. Two new methods were developed to prepare indium phosphide nanowires from red phosphorus and phosphorus pentabromide via Solution-Liquid-Solid growth. Borohydride reagents are required in both methods to produce chemically active intermediates which further react to form indium phosphide nanowires in the presence of pre-synthesized indium metal or bismuth nanoparticles. The diameter of indium phosphide nanowires prepared from red phosphorus depends strongly on the reaction sequences. If indium metal nanoparticles are formed prior to the addition of red phosphorus, large nanowires (> 300 nm) are produced. Reversing the sequences, small nanowires (50-100 nm) are produced. Red phosphorus residue remains in the products regardless of the reaction sequences and is difficult to remove completely by chemical means. The reaction which employs phosphorus pentabromide as precursor proceeds via intermediates of hydrogen phosphide and indium metal to form indium phosphide. The reaction temperature dictates the crystallinity of the product and needs to be >170 oC to produce crystalline indium phosphide. The way hydrogen phosphide is introduced to the reaction and the presence or absence of pre-synthesized metal seeds together control the morphology of indium phosphide synthesized. The best set of conditions established in this thesis allows the preparation of indium phosphide in ~100% nanowire morphology. The hydrogen phosphide method was adapted to produce zinc phosphide nanoparticles. The choice of the reaction solvent was found to be most critical. Amorphous particles were produced in trioctylphosphine at as high as 330 oC whereas in oleylamine and N,Ndiethylaniline crystalline zinc phosphide (a-Zn3P2) nanoparticles were produced at ~200 oC. An overall conclusion is given in the last chapter comparing the methods developed in this thesis with literature methods paying particular foci on the level of hazard and the costs of the chemical reagents involved.</p>

Solution Phase Syntheses of Nanoparticles and Nanowires

<p>This thesis is concerned with the preparation of metal and semiconductor nanostructures in solution, specifically bismuth and indium metal nanoparticles, gallium nitride nanoparticles, indium phosphide nanowires and zinc phosphide nanoparticles. There were two aims: firstly to study if gallium nitride nanoparticles with improved crystallinity and size distribution could be synthesized and secondly to find and develop new methods to prepare crystalline indium phosphide nanowires and zinc phosphide nanoparticles using precursors that are safe and cheap. The crystallinity, structures, morphologies and chemical compositions of the nanostructures synthesized in this thesis were studied primarily by transmission electron microscopy (TEM), powder X-ray diffraction (PXRD) and energy dispersive X-ray spectrometry (EDS). For the synthesis of gallium nitride, two approaches were taken. The first revolves around the direct metathesis reaction between gallium trichloride and lithium nitride under ambient pressure. A range of solvents with different polarities has been tested and only in highly polar solvents crystalline nanostructures were produced. These crystalline nanostructures however are not of gallium nitride. The second approach involves thermally decomposing an organometallic precursor. Organometallic compounds [Ga2(NMe2)6] (compound 1) and [(Me3C)2Ga(u-NHNHCMe3)] (compound 2) were chosen from the literature as precursors. Compound 1 was synthesized in a very small yield together with by-products. Thermal decomposition of the mixture produced no nanoparticles. A compound (compound S2) which is structurally similar to compound 2 was successfully synthesized and was subjected to thermal decomposition in ammonia to produce crystalline monodispersed nanoparticles. However, these nanoparticles could not be confidently identified as gallium nitride. The outcome from the reaction of lithium borohydride and indium trichloride was found to be strongly solvent dependent. In toluene a white precipitate was obtained. Both in isobutylamine and N,N-diethylaniline indium metal nanoparticles were produced as black solutions. Only in isobutylamine, small monodispersed indium nanoparticles can be produced. The isobutylamine method was extended to prepare bismuth metal nanoparticles. However, the bismuth nanoparticles prepared were moderately polydispersed in size. Two new methods were developed to prepare indium phosphide nanowires from red phosphorus and phosphorus pentabromide via Solution-Liquid-Solid growth. Borohydride reagents are required in both methods to produce chemically active intermediates which further react to form indium phosphide nanowires in the presence of pre-synthesized indium metal or bismuth nanoparticles. The diameter of indium phosphide nanowires prepared from red phosphorus depends strongly on the reaction sequences. If indium metal nanoparticles are formed prior to the addition of red phosphorus, large nanowires (> 300 nm) are produced. Reversing the sequences, small nanowires (50-100 nm) are produced. Red phosphorus residue remains in the products regardless of the reaction sequences and is difficult to remove completely by chemical means. The reaction which employs phosphorus pentabromide as precursor proceeds via intermediates of hydrogen phosphide and indium metal to form indium phosphide. The reaction temperature dictates the crystallinity of the product and needs to be >170 oC to produce crystalline indium phosphide. The way hydrogen phosphide is introduced to the reaction and the presence or absence of pre-synthesized metal seeds together control the morphology of indium phosphide synthesized. The best set of conditions established in this thesis allows the preparation of indium phosphide in ~100% nanowire morphology. The hydrogen phosphide method was adapted to produce zinc phosphide nanoparticles. The choice of the reaction solvent was found to be most critical. Amorphous particles were produced in trioctylphosphine at as high as 330 oC whereas in oleylamine and N,Ndiethylaniline crystalline zinc phosphide (a-Zn3P2) nanoparticles were produced at ~200 oC. An overall conclusion is given in the last chapter comparing the methods developed in this thesis with literature methods paying particular foci on the level of hazard and the costs of the chemical reagents involved.</p>

Effects of background food on alternative grain uptake and zinc phosphide efficacy in wild house mice

BACKGROUND: House mice (Mus musculus) cause significant, ongoing losses to grain crops in Australia, particularly during mouse plagues. Zinc phosphide (ZnP) coated grain is used for control, but with variable success. In a laboratory setting, we tested if mice would (1) switch from consumption of one grain type to another when presented with an alternative, and (2) consume ZnP-treated grains when presented as a choice with a different grain. RESULTS: Mice readily switched from their background grain to an alternative grain, preferring cereals (wheat or barley) over lentils. Mice readily consumed ZnP-coated barley grains. Their mortality rate was significantly higher (86%, n=30) in the presence of a less-favoured grain (lentils) compared to their mortality rate (47%, n=29; and 53%, n=30) in the presence of a more-favoured grain (wheat and barley, respectively). Mice died between 4-112 h (median = 18 h) after consuming one or more toxic grains. Independent analysis of ZnP-coated grains showed variable toxin loading indicating that consumption of a single grain would not guarantee intake of a lethal dose. There was also a strong and rapid behavioural aversion if mice did not consume a lethal dose on the first night. CONCLUSIONS: The registered dose rate of 25 g ZnP/kg wheat; ~ 1 mg ZnP/grain in Australia needs to be re-evaluated to determine what factors may be contributing to variation in efficacy. Further field research is also required to understand the complex association between ZnP dose, and quantity and quality of background food on efficacy of ZnP baits.