Influence of select bioenergy by-products on soil carbon and microbial activity: A laboratory study.

Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state 13C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time.

Seed train development for the fermentation of bagasse from sweet sorghum and sugarcane using a simplified fermentation process.

A process was developed for seed culture expansion (3.6 million-fold) using 5% of the hemicellulose hydrolysate from dilute acid pretreatment as the sole organic nutrient and source of sugar. Hydrolysate used for seed growth was neutralized with ammonia and combined with 1.0mM sodium metabisulfite immediately before inoculation. This seed protocol was tested with phosphoric acid pretreated sugarcane and sweet sorghum bagasse using a simplified process with co-fermentation of fiber, pentoses, and hexoses in a single vessel (SScF). A 6h liquefaction (L) step improved mixing prior to inoculation. Fermentations (L+SScF process) were completed in 72 h with high yields (>80 gal/US ton). Ethanol titers for this L+SScF process ranged from 24 g/L to 32 g/L, and were limited by the bagasse concentration (10% dry matter).

Photosynthetic consequences of Marssonina leaf spot differ between two poplar hybrids.

• In foliage of two hybrid poplars, clone DN-34 (Populus deltoides × P. nigra) and clone NM-6 (P. nigra × P. maximowiczii), we examined relationships between photosynthesis and severity of leaf spot induced by Marssonina brunnea f. sp. brunnea, a common disease of many tree species in the Populus genus with the potential to affect growth. • Gas exchange was measured on asymptomatic and diseased foliage in monoculture stands of each clone. The equation Y = (1 - x)ß was used to characterize the relationship between relative photosynthesis (Y) and percent leaf spot (x), where ß represents the ratio between functional impairment and measured lesion area. • Leaf photosynthesis was strongly and negatively correlated with leaf spot severity in both hybrids, and ß-values indicated that photosynthetic impairment extended beyond visibly damaged leaf tissue. However, large differences in ß between hybrids indicated differential photosynthetic consequences for a given leaf spot severity. For each hybrid, values of ß were positively related to photosynthetic photon flux density incident upon the leaf during gas exchange measurement. • Declines in leaf photosynthesis appeared to result from a disruption of the photosynthetic apparatus by the invading pathogen. However, specific causes for the differential photosynthetic responses of the two hybrids to disease remained elusive.

Pseudo-symmetrical difluoroketones. Highly potent and specific inhibitors of HIV-1 protease.

A series of novel, pseudo-symmetrical difluoroketones which are highly potent inhibitors of the HIV-1 protease (IC50 = 1.55-0.02 nM) were synthesized. These compounds also possess good antiviral activity by inhibition of the cytopathic effect of HIV-13B in MT-4 cells in vitro.

Cost and procedure implications of thrombolytic therapy for acute myocardial infarction.

A computer model was developed to analyze the costs to Medicare and the potential procedure volume associated with alternative strategies for treatment of acute myocardial infarction. The expected cost per case to Medicare for initial hospitalization was approximately $7,200 for conventional treatment, $7,900 for treatment with intravenous streptokinase and $8,400 for treatment with recombinant tissue-type plasminogen activator (rt-PA). The expected cost per case for use of streptokinase or rt-PA in combination with cardiac catheterization performed either emergently or at 48 h was in excess of $11,000. These cost estimates do not reflect the cost of thrombolytic drugs themselves because Medicare has not adjusted its hospital payment rates to take account of such costs. Although both streptokinase and rt-PA will increase costs to Medicare for hospitalizations for acute myocardial infarction, both agents will do so at a reasonably low cost per additional life saved--between $50,000 and $60,000. Emergency and 48 h catheterization strategies are considerably less cost-effective. Regarding procedures, this model suggests that for every 1,000 patients treatment with streptokinase will result in an additional 76 coronary angioplasty procedures and 26 coronary artery bypass operations, whereas treatment with rt-PA will result in an additional 122 angioplasty procedures and 43 bypass operations compared with conventional treatment. Thrombolytic treatment is thus likely to increase substantially the volume of cardiac catheterization, coronary angioplasty and coronary artery bypass surgery performed in the United States.

Contrast medium-induced adverse reactions: economic outcome.

Because the cost of managing an expected greater number of adverse reactions when high-osmolality contrast media (HOM) are used could offset the higher material cost of low-osmolality contrast media (LOM), a prospective study was done of 795 inpatients undergoing any of four procedures involving intravascular injection of HOM: cardiac catheterization, peripheral angiography, head computed tomography (CT), or body CT. The resources used in managing HOM-induced adverse reactions were measured, and the costs of these resources were estimated. Four hundred five patients (51%) had adverse reactions. Reactions were grouped into three classes according to their severity. Class 1 (mild) reactions occurred in 358 patients (45%), class 2 (moderate) reactions occurred in 44 patients (6%), and class 3 (severe) reactions occurred in three patients (0.4%). Ninety-nine patients (12%) consumed resources as a result of an adverse reaction. The average cost of these resources per patient undergoing examination was $1.07 to the radiology department, $5.83 to the hospital, and $12.93 to a charge-paying insurer. Mean (+/- standard deviation) cost to the hospital for managing class 1, class 2, and class 3 reactions were $2.52 +/- $5.33, $24 +/- $54, and $910 +/- $749, respectively. By comparison, the difference in material cost of HOM versus LOM ranged from $93 for body CT to $179 for cardiac catheterization. Even if LOM were to induce no adverse reactions, the increased material cost associated with universal substitution of LOM for HOM would be greater than the expected cost of managing adverse reactions when HOM are used.

Prospective payment for capital: an examination of current issues.

Congress has suggested that a prospective payment system for capital should permit the continuation of cost-based reimbursement for certain projects. A study was conducted to examine the components of the capital planning process used by eight hospitals and the effect of this process on completion of capital projects.

New medium for rapid screening and enumeration of Clostridium perfringens in foods.

A rapid and sensitive procedure for estimating low numbers of Clostridium perfringens has been investigated and compared to methods used currently in the food industry. The new liquid medium, RPM (rapid perfringens medium), was compared with sulfite-polymyxin-sulfadiazine agar and tryptose-sulfite-cycloserine agar in recovery studies with naturally contaminated and with inoculated foods. The medium consists of a mixture of litmus milk and fluid thioglycolate medium fortified with glucose, peptone, gelatin, yeast extract, sodium chloride, and ferrous sulfate. Selectivity is based on an antibiotic system (polymyxin B sulfate and neomycin sulfate) incorporated into the medium, coupled with an incubation temprature of 46 to 48 degrees C for 24 h. Tubes were scored as positive if a stormy fermentation was observed. All tubes demonstrating stormy fermentation were confirmed as containing C. perfringens. Of a total of 774 naturally contaminated food samples, 546 samples (71%) were found to contain C. perfringens with RPM, whereas only 168 (22%) of the samples were positive using sulfite-polymyxin-sulfadiazine agar. C. perfringens was isolated from 71% of 85 other samples using RPM as compared to 14% with tryptose-sulfite-cycloserine agar. Enumeration studies on 14 individual samples using the most probable number technique also demonstrated greater sensitivity with RPM.