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SynopsisA study has been carried out of the performance and chemical characteristics of composite reverse osmosis membranes prepared by plasma polymerization of allylamine in a radiofrequency electric discharge. It has been shown that membranes can be prepared which simultaneously exhibit a high rejection for sodium chloride and a high water flux. The primary factors influencing the quality of the membranes are the choice of substrate material, the d+ position time, and the power supplied to the discharge. Variations in rejection and flux as a function of applied pressure indicate that water flows through the membrane by both diffusive and bulk flow. A reduction in rejection and an increase in flux are observed when membranes are operated for prolonged periods or a t higher temperatures (up to 60°C). Elemental analysis of plasma-polymerized allylamine shows that it can be represented by the stoichiometry C3Ha.8N0.900.1. Infrared spectra show evidence for N-H, C=N, C=N, and C-H bond vibrations. ESCA spectra of the polymer surface show that the surface contains substantial amounts of both nitrogen and oxygen and that the nitrogen is present as either a nitrile or an imine group but not as an amine group. ESCA spectra of membranes used for reverse osmosis show that the surface loses nitrogen and gains oxygen with time and that this phenomenon is accelerated a t higher operating temperatures. A decrease in rejection and an increase in flux accompanies these changes. It is postulated that most of the nitrogen in the polymer is present in the form of RR'C=NH or RR'C=NR" type structures. The loss of nitrogen and gain in oxygen observed in the ESCA spectra of membranes run a t elevated temperatures is explained by the hydrolysis of the proposed structures.

Improvements in cultivars and management technology have increased the yield potential of soft red winter wheat (SRWW) (Triticum aestivum L.). Field experiments were conducted for 3 yr to define fertilizer requirements for doublecrop SRWW grown on Sharkey clay soil (Vertic Haplaquent). Nitrogen rates were 0, 34,56,78, and 101 kg ha−1 applied as both a single February topdress application (growth stage 5, Feeke's scale) and as a fall‐February split with 17 kg of the total N applied preplant. The effects of application of P (20 kg ha−1) and K (24 kg ha−1) were evaluated singly and in combination at a February applied N rate of 56 kg ha−1 and fall + February split N application rates of 17 + 39 and 17 + 62 kg N ha−1. Significant yield increases were obtained from applied N up to the maximum rate of 101 kg ha−1. The best estimate of yield ( Y) plotted against N rate (X) was the linear equation Y = 3002 + 9.9 × (R2=0.98). Kernels per spike increased and specific kernel weight decreased slightly with N application. There was no yield benefit from splitting the total applied N. Leaf rust (Puccinia recondita Rab. ex Desm.) and powdery mildew (Erysiphe graminis D.C.) infection showed a positive linear association with increasing N rate (R2=0.77 and 0.42, respectively). Phosphorus fertilization decreased the incidence of both leaf rust and powdery mildew. Nitrogen, at the rates applied in this study, did not affect grain protein content but did increase total protein per hectare by increasing yield. Nitrogen fertilization increased the S content of grain and tended to decrease P and K content. Phosphorus and K had no effect on grain protein or mineral composition.

The technique of plasma polymerization under vacuum conditions at ~0.1 Torr has been employed to produce highly moisture resistant, thin polymer films on hygroscopic alkali metal halide crystal materials. The polymer film is fluorocarbon in nature. In addition to the moisture resistance, the films also exhibit antireflection properties and have only one absorption band over the range 25,000-250 cm(-1) centered at 1200 cm(-1).

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New Light Weight Ceramic Ablators (LCAs) were produced by using ceramic and carbon fibrous substrates impregnated with silicone and phenolic resins. Special infiltration techniques (patent pending) were developed to control the amount of organic resin in the highly porous fiber matrices, so that the final densities of LCAs range from 0.224 to 0.30 g/cu cm. This paper presents the thermal and ablation performance of the Silicone Impregnated Reusable Ceramic Ablators (SIRCA) in a simulated Mars entry heating environment. Testing was conducted in the Ames 60 MW Interaction Heating Facility (IHF) and 20 MW Aerodynamic Heating Facility (AHF). Test results show that the ablation characteristics of SIRCA are divided into three regimes: non-receding, surface coalescent, and receding. Four different Reusable Surface Insulation (RSI) substrates were used in the production of SIRCA to determine the effect of substrate compositions on the ablation performance. SIRCA with high-purity silica fibers generally performed better at high heating rates. Samples of SIRCA were tested at heating rates ranging from 45 to 550 W/sq cm and at stagnation pressures of 0.02 to 0.47 atm. Several samples were also tested at a heating environment simulating the Mars Aerocapturing mission, which generally consists of a low heating rate and a very high heat load. Material characterizations were also conducted to evaluate the material's mechanical, thermal, and optical properties. The effective thermal conductivity of SIRCA is comparable to that of the RSI substrates, and the emissivity of the charred SIRCA was measured to be about 0.92. Several samples of SIRCA were also exposed to the same heating condition for five cycles, and no additional significant mass loss or recession was observed. (Author) Abstract New Light Weight Ceramic Ablators (LCAs) were produced by using ceramic and carbon fibrous substrates impregnated with silicone and phenolic resins 1 . Special infiltration techniques (patent pending) were developed to control the amount of organic resin in the highly porous fiber matrices, so that the final densities of LCAs range from 0.224 to 0.30 g/cm 3 . This paper presents the thermal and ablation performance of the Silicone Impregnated Reusable Ceramic Ablators (SIRCA) in a simulated entry heating environment for Mars entry. Testing was conducted in the Ames 60 MW Interaction Heating Facility (IHF) and 20 MW Aerodynamic Heating Facility (AHF). Test results show that the ablation characteristics of SIRCA are divided into three regimes -non-receding, surface coalescent, and receding. Four different Reusable Surface Insulation (RSI) substrates were used in the production of SIRCA to determine the effect of substrate compositions on the ablation performance. SIRCA with high purity silica fibers generally performed better at high heating rates. Samples of SIRCA were tested at heating rates ranging from 45 to 550 W/cm 2 and at stagnation pressures of 0.02 to 0.47 atm. Several samples were also tested at a heating environment simulating the Ma...

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