Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N) and arsenic (As), which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity.

Development of a new slow-release micronutrient fertilizer of iron−manganese is described. Studies include formulation, synthesis, kinetics, characterization, and testing. The compound is a partially polymerized, iron−manganese−magnesium polyphosphate, which is produced at 200 °C by reaction of iron, manganese, and magnesium oxides with phosphoric acid, followed by neutralization to pH 5.6. Polymerization is optimal at 21.2% with an Fe/Mn/Mg/P molar ratio of 1:0.51:1.15:7.33. Condensation kinetics show multistage processes with plateau formation at the end of each stage. The compound is crystalline with new XRD patterns indicative of a regular arrangement of polyphosphate chains. ESR spectra reveal Mn predominantly in the IV state. The product has ideal slow-release characteristics of low water solubility but high citrate and DTPA solubility, indicating high bio-availability of the micronutrients. Plant trials with chilli show a 45.6% increase in yield, at Fe 2 kg/ha−Mn 1 kg/ha as the slow-release fertilizer. The compound appears to be a promising, environmentally friendly alternative for Fe−Mn fertilization.

This paper describes a new water-insoluble molybdenum compound that has been developed as a slow-release fertilizer. The compound is an inorganic polymer formed by inclusion of molybdenum within a long-chain polyphosphate structure. It was designed by a process of "reverse engineering" of the molecule. Synthesis involved reaction of phosphoric acid with magnesium oxide, molybdenum trioxide, and sodium carbonate at 275 degrees C. Kinetics of reaction revealed complex multistage processes. X-ray diffraction patterns showed a crystalline nature with short-range as well as long-range ordering. The magnesium sodium polymolybdophosphate had ideal slow-release characteristics; it had low water solubility and high citrate solubility and was powdery, free flowing, and nonhygroscopic. Field testing showed an 80% increase in yield of green gram at a low dose of 0.04 kg/ha Mo. Nodulation increased by over 161%, and N content of gram increased by 20%. The slow-release fertilizer would provide an effective, low-cost, and environmentaly friendly alternative to Mo fertilization.

A novel freeze-drying protocol has been explored to render fast and cost-effective freeze drying of hyperamylase producing Bacillus subtilis MTCC2396 employing a tungsten halogen lamp radiator (THLR) as a heat source. Response surface methodology assessed the maximum reduction in moisture content (96.07%) and minimum reduction in a-amylase (EC 3.2.1.1) activity (1.02%) in 4 h drying time at 42.5 C radiation temperature. a-amylase activity (0.046 U) and final moisture content (3.93%) of the optimally freeze-dried bacterial strain appeared satisfactory. The freeze-drying time using THLR (4 h) is remarkably lower compared to that under a conventional conductive plate heater (CPH) (10 h) at otherwise identical conditions. The higher effective moisture diffusivity of 0.0052 to 0.0078 m 2 /s under THLR compared to 0.00084 to 0.0015 m 2 /s under CPH (corresponding to 20-50 C) advocated the superiority of the THLR heating protocol. The higher efficacy of THLR was also evidenced through lower activation energy (8.42 kJ/mol) of moisture diffusion compared to that (12.051 kJ/mol) of CPH. The optimally freeze-dried bacteria demonstrated the same growth rate in addition to exhibiting excellent retention of bioremedial (Hg 2þ removal) activity to that of the control.

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