Heat capacity and vapor-pressure measurements indicate a higher-order phase transition in nitrogen monolayers adsorbed on basal-plane graphite. The transition coincides with finite jumps in three experimental quantities: the two-dimensional compressibility, the isosteric heat of adsorption, and the heat capacity at constant area. Thermodynamics implies that the heat capacity at constant two-dimensional spreading pressure also has an abrupt jump and hence the transition is suggestive of a second-order Ehrenfest type.
The excessive viral diversity noted by Heath et al . in our sample of infected HIV patients prompted us to reexamine our data. Doing so uncovered several mislabeled samples, but no sources of contamination were identified. Investigations into additional transmission pairs will be needed to further investigate these issues.
Abstract. High tunnels (HTs) are used worldwide for greater crop sustainability and profitability, but producers are finding it difficult to control the trapped heat inside HTs. Clearly, proper ventilation management is crucial for obtaining marketable yield and quality, but the ability to predict HT ventilation based solely on external climate parameters is limited. This project analyzes daytime ventilation rates in a Gothic-type HT located in eastern Tennessee. A numerical energy balance model was developed to calculate air flux, and the estimated values of air flux were compared with measured values from sonic and hot-wire anemometers. Uniquely, this study takes into account the sensible and latent heat exchanges between inside and outside conditions, the radiative and convective transfer mechanisms, and the effects of external wind conditions on the incoming air flux. Moreover, relationships between the external weather conditions and internal microclimate were developed so that air flux, inside temperature, and door opening level could be predicted with the energy balance model using only external weather data. The energy balance model revealed that the HT plastic surface reflected nearly 20% of the solar radiation, that 1% of the solar energy was stored in the air (considered negligible), and that 5% of the solar energy was stored in the soil, while the majority of available solar radiation, 74%, was removed through natural ventilation. There was good agreement between the predictive energy balance model and the direct air flux calculation for ventilation rate (R 2 > 0.70). At the windward end of the HT, the airflow entering the door was mostly perpendicular to the plane of the door opening, which indicated that the fluctuation of outside wind direction had limited effect on the airflow patterns through the door. As a significant indicator of the energy balance model’s usefulness, the predicted inside air temperature was validated as similar to the measured values. Thus, the results showed strong evidence that the coupling of the energy balance model and air flux calculation based on external weather parameters can be a valuable method to predict inside microclimate conditions and can be used to estimate the door opening level. Keywords: Air flux, Energy balance, High tunnel, Natural ventilation.
Alternatives to soil fumigation are needed for soilborne disease control. The aim of this study was to test anaerobic soil disinfestation (ASD) as an alternative to soil fumigation for control of critical soilborne pathogens in Californian strawberry production. Controlled environment experiments were conducted at 25 and 15 °C to test different materials as carbon sources for ASD using soil inoculated with Verticillium dahliae . Field trials were conducted in three locations comparing ASD with 20 Mg ha −1 rice bran (RB) against fumigated and untreated controls, steam, mustard seed meal and fish emulsion. In ASD‐treated soils, temperature and extent of anaerobic conditions were critical for control of V. dahliae , but multiple carbon inputs reduced inoculum by 80–100%. In field trials, ASD with RB provided control of a number of pathogens, and in three of four trials produced marketable fruit yields equivalent to fumigation. Little weed control benefit from ASD was found. ASD with RB also induced changes in the soil microbiome that persisted through the growing season. When equivalent yields were obtained, net returns above harvest and treatment costs with ASD RB were 92–96% of those with bed fumigation based on average prices over the previous 5 years. ASD can be a viable alternative for control of some soilborne pathogens. Growers are adopting ASD in California strawberry production, but research to determine optimal soil temperatures, anaerobicity thresholds and carbon sources for effective control of specific pathogens is needed.
Anaerobic soil disinfestation (ASD) is a promising alternative to chemical fumigation for controlling soilborne plant pathogens and weeds. This study investigated the impact of brewer’s spent grain (BSG), a locally available carbon source, on various weed species and the oomycete pathogen Pythium irregulare in ASD. Two greenhouse studies were conducted using BSG and yeast at full and reduced rates in a completely randomized design with four replicates and two runs per study. In both studies, ASD treatments significantly decreased the seed viability of all weed species and the Pythium irregulare inoculum, while promoting higher cumulative anaerobicity compared to the non-treated control. The addition of yeast had a notable effect when combined with BSG but not with rice bran. When used in reduced carbon rates, yeast supplementation enhanced the efficacy of BSG, providing comparable control to the full rate for most weed species, including redroot pigweed, white clover, and yellow nutsedge. Interestingly, no ASD treatment affected the soil temperature. Furthermore, BSG treatments caused higher concentrations of volatile fatty acids compared to ASD with rice bran and the non-treated control. This finding suggests that the inclusion of yeast in ASD shows potential for reducing the carbon input required for effective soil disinfestation.
Background: Frequent methamphetamine use among recently HIV infected individuals is associated with transmitted drug resistance (TDR) to non-nucleoside reverse transcriptase inhibitors (NNRTI); however, the reversion time of TDR to drug susceptible HIV may exceed 3 years. We assessed whether recreational substance use is associated with detectable TDR among individuals newly diagnosed with HIV infection of unknown duration.
The results of an exhaustive high-precision heat-capacity study of the submonolayer regime of the krypton-graphite (Grafoil) adsorption system are presented. A phase diagram exhibiting a single two-phase coexistence region is proposed as an alternative to the previously proposed triple-point phase diagram. A quantitive correspondence between the locus of heat capacity anomalies in the Kr-graphite system and that for the ${\mathrm{N}}_{2}$-graphite system suggests the proposed phase diagram may apply to the ${\mathrm{N}}_{2}$ system as well.
