Carbodiimide-Driven Toughening of Interpenetrated Polymer Networks.

Recent work has demonstrated that temporary crosslinks in polymer networks generated by chemical "fuels" afford materials with large, transient changes in their mechanical properties. This can be accomplished in carboxylic-acid-functionalized polymer hydrogels using carbodiimides, which generate anhydride crosslinks with lifetimes on the order of minutes to hours. Here, the impact of the polymer network architecture on the mechanical properties of transiently crosslinked materials was explored. Single networks (SNs) were compared to interpenetrated networks (IPNs). Notably, semi-IPN precursors that give IPNs on treatment with carbodiimide give much higher fracture energies (i.e., resistance to fracture) and superior resistance to compressive strain compared to other network architectures. A precursor semi-IPN material featuring acrylic acid in only the free polymer chains yields, on treatment with carbodiimide, an IPN with a fracture energy of 2400 J/m2, a fourfold increase compared to an analogous semi-IPN precursor that yields a SN. This resistance to fracture enables the formation of macroscopic complex cut patterns, even at high strain, underscoring the pivotal role of polymer architecture in mechanical performance.

Evaluation of Two Disease Warning Systems for Botryosphaeria Panicle and Shoot Blight of California Pistachio and Efficient Control Based on Early-Season Sprays.

Two empirical models to predict infection events were evaluated for control of Botryosphaeria panicle and shoot blight, caused by a Fusicoccum sp., as well as the effectiveness of early-season fungicide sprays on the control of this disease of pistachio. A model incorporating wetness duration was superior to one based solely on duration of rains ≥1 mm/h for ≥4 h and with temperature ≥11°C. The wetness duration threshold (W) for rain events ≥4 mm at a given temperature (T) for high-risk infection events was W = -7.8 + 397/T and the threshold for medium-risk events was W = -6.9 + 220/T. Wet periods interrupted by ≤12 h were added together to calculate W. In two orchards with high levels of inoculum, one high-risk event resulted in 20 to 23% blighted fruit at harvest and two or three high-risk events resulted in 31 to 80% blighted fruit. Latent infections were 0 to 1% in instances where only low-risk events (one to two events) occurred prior to collection of pistachio fruit for determination of latent infections and were 17 to 36% with one to three high-risk events. Early-season fungicide sprays in April to May effectively controlled panicle and shoot blight when applied up to 12 days before predicted infection events or 5 days after.

Presentation of gastric carcinoma on a radionuclide gastric-emptying study.

We present a case of unsuspected gastric carcinoma discovered as a result of abnormalities seen on a sulfur colloid gastric-emptying study. Considered a functional or physiological analysis, often relatively little attention is given to the morphology of the stomach except for the purpose of drawing a region of interest. This case, in which the images suggested a space-occupying lesion(s), emphasizes the importance of careful examination for "pathoanatomy" as well as pathophysiology in functional imaging.

Inoculum dynamics, fruit infection, and development of brown rot in prune orchards in california.

ABSTRACT Brown rot, caused by Monilinia fructicola, is a destructive disease of stone fruit in California. Disease management requires information on inoculum dynamics and development of latent and visible fruit infections during the season to help make decisions on timing of fungicide treatments and choice of cultural practices. In this study, the daily spore concentration (ascospores and conidia) of M. fructicola in the air was monitored with spore traps in two prune orchards during the growing seasons in 2001 and 2002. The spore concentrations were low to moderate at early bloom, increased at full bloom, and decreased to the lowest level at the end of bloom. Improper timing of fruit thinning and irrigation in midseason increased spore concentration in the air and fruit infections late in the season. Artificial fruit inoculations were conducted periodically in 10 prune orchards in 2002 and 2004, and incidence of fruit rot at different inoculation dates was assessed. Fruit rot development rate increased linearly with inoculation date during the growing season. Natural blossom and fruit infections were monitored periodically in 10 prune orchards, and incidence of latent fruit infection was determined by using the overnight freezing-incubation technique. Incidence of fruit rot also was assessed 2 weeks before harvest in these orchards. The incidence of latent fruit infection at the pit hardening stage significantly correlated with that at the late stages and with the incidence of fruit rot at harvest.

Effects of Timing of Copper Sprays, Defoliation, Rainfall, and Inoculum Concentration on Incidence of Olive Knot Disease.

The olive knot pathogen, Pseudomonas savastanoi, causes galls on shoots, branches, fruit, and leaves. Shoots girdled by galls die. Any fresh wound is susceptible to infection, but the most common entry sites are leaf scars. Leaf scars are most susceptible to infection during the first 2 days after leaf fall and remain susceptible for 7 more days. Simulated leaf scars on 'Manzanillo' olive trees were created by removing leaves from healthy shoots at approximately monthly intervals from December through June 1997-98, 1998-99, and 1999-2000. Trees were treated with a water suspension of cupric hydroxide (Kocide DF40) at 3 g/liter one, two, or three times in 1998-99 and 1999-2000 with a hand-gun sprayer. Generally, disease control improved with more applications (P = 0.008 and 0.032 in 1999 and 2000, respectively). Disease incidence was greatest on shoots that were defoliated in March 1998, April and June 1999, and March and May 2000. Cumulative rainfall 2 and 9 days after each defoliation was recorded. Disease incidence was positively correlated (P = 0.031 and 0.023 for 2 and 9 days, respectively) with spring (March through June) but not winter (December through February) rainfall. Comparable simulated leaf scars were inoculated in December and April 1997-98 and 1998-99 with 104, 106, and 108 CFU/ml of the pathogen and treated with a water suspension of cupric hydroxide at 3 g/liter using a handheld pump sprayer. Inoculated and noninoculated, nontreated shoots were included. More disease developed in April than in December inoculations (P = <0.0001) in both years. Disease incidence increased with increasing inoculum concentration (P = <0.0001) in both years and was lower in shoots treated with Kocide DF40 (P = <0.0001). Our work demonstrated that the common grower practice of one post-harvest application of copper bactericide provides only minimal protection against olive knot, and that additional sprays in spring are needed to substantially improve disease control.