The Plant Stress Hypothesis and Variable Responses by Blue Grama Grass (<Emphasis Type="Italic">Bouteloua gracilis</Emphasis>) to Water,Mineral Nitrogen,and Insect Herbivory

Acting simultaneously or sequentially, plants encounter multiple stresses from combined abiotic and biotic factors that result in decreased growth and internal reallocation of resources. The plant stress hypothesis predicts that environmental stresses on plants decrease plant resistance to insect herbivory by altering biochemical source–sink relationships and foliar chemistry, leading to more palatable food. Such changes in the nutritional landscape for insects may facilitate insect population outbreaks during periods of moderate stress on host plants. We examined the plant stress hypothesis with field experiments in continental grassland (USA) using the C₄ grass Bouteloua gracilis. Water, nitrogen fertilizer, and herbivory from the grass-feeding grasshopper Ageneotettix deorum were manipulated. Combined stresses from water and mineral-N in the soil decreased plant growth and altered foliar percent total N (TN) and percent total nonstructural carbohydrate (TNC) concentrations in an additive fashion. Grasshopper herbivory affected final biomass only in dry years; plants compensated for tissue loss when rainfall was abundant. Foliar TN and TNC concentrations were dynamic with respect to variable climatic conditions and treatment combinations, showing significant interactions. Grasshopper herbivory had its greatest impact on TN or TNC in dry years, interacting with other forms of stress. Herbivory as a single factor had strong effects on TNC in years with normal precipitation, but not in a dry year. Performance (developmental rate and survival) by the grasshoppers Phoetaliotes nebrascensis and A. deorum were not greatly affected by plant stress in a manner consistent with the plant stress hypothesis.     

Aristoforin, a novel stable derivative of hyperforin, is a potent anticancer agent

Hyperforin, a natural product of St. John's wort (Hypericum perforatum L.), has a number of pharmacological activities, including antidepressive and antibacterial properties. Furthermore, hyperforin has pronounced antitumor properties against different tumor cell lines, both in vitro and in vivo. Despite being a promising novel anticancer agent, the poor solubility and stability of hyperforin in aqueous solution limits its potential clinical application. In this study, we present the synthesis of hyperforin derivatives with improved pharmacological activity. The synthesized compounds were tested for their solubility and stability properties. They were also investigated for their antitumor properties, both in vitro and in vivo. One of these hyperforin derivatives, Aristoforin, is more soluble in aqueous solution than hyperforin and is additionally highly stable. Importantly, it retains the antitumor properties of the parental compound without inducing toxicity in experimental animals. These data strongly suggest that Aristoforin has potential as an anticancer drug.     

Fabrication of catalytic membranes for the treatment of drinking water using combined ozonation and ultrafiltration

The removal of disinfection byproducts and their precursors was investigated using a combined ozonation-ultrafiltration system. A commercial membrane was coated 20 or 40 times with iron oxide nanoparticles (4-6 nm in diameter). With this membrane, the concentration of dissolved organic carbon was reduced by >85% and the concentrations of simulated distribution system total trihalomethanes and simulated distribution system halo acetic acids decreased by up to 90% and 85%, respectively. When the coated membrane was used, the concentrations of aldehydes, ketones, and ketoacids in the permeate were reduced by >50% as compared to that obtained with the uncoated membranes. Hydroxyl or other radicals produced at the iron oxide coated membrane surface as a result of ozone decomposition are believed to have enhanced the degradation of the natural organic matter, thereby reducing the concentration of disinfection byproducts. While increasing the number of times the membrane was coated from 20 to 40 did not significantly reduce the concentrations of most of the parameters measured, it did result in a significant decrease in the concentrations of ozonation byproducts. Increasing the sintering temperature from 500 to 900 degrees C also resulted in an improvement in the removal of the ozonation byproducts.     

Status of gas-cooled fast breeder reactor programs

Most gas-cooled fast breeder reactor (GCFR) programs in Europe and the US are now coordinated and focused on a 300 MW(e) GCFR demonstration plant program. Except for venting and artificial surface roughening, GCFR fuel is similar to liquid metal fast breeder reactor (LMFBR) fuel and operates under nearly identical conditions. The primary helium system is integrated within a PCRV like all large gas-cooled thermal reactors, with three main loops and three auxiliary loops. Design and safety studies and various experiments, including heat transfer, irradiation, and critical experiments, indicate that most feasibility questions have been answered and a demonstration plant could be in operation within 12 years. This could be followed in the mid-1990s by a large-size GCFR with a doubling time of about 10 years fueled by (UO₂---PuO₂) and producing either ²³³U in thorium blankets as fuel for advanced converters or plutonium in depleted uranium blankets.     

Effect of Tranquilizers on the Trail Making Test with Chronic Schizophrenics.

46 chronic schizophrenics with at least 3 years of continuous hospitalization, no secondary diagnosis of brain damage, age under 59, and all stabilized on their current medication were tested twice on the Trail Making Test (TMT) with 6 wk. between testings. The experimental group (N = 28) had the 2nd testing, following 5 weeks of being off all drugs. Results show: (a) previous findings that TMT is not a sensitive test for organicity with schizophrenics are true whether or not Ss are on tranquilizers, (b) no relationship between amount of drugs and performance on TMT, and (c) drug withdrawal did not affect performance on TMT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biomedical Instrumentation for the Measurements of Skin Sensitivity

This paper reports on the development of two techniques designed to measure the electric responses to periodic tactile and thermal0 stimuli on the skin of the hand.     

An experimental study of surface-tension induced convection at reduced gravity

Fluid motions are induced by surface-tension gradients on the free surface of a liquid in a cylindrical container which is in free fall in a drop tower. Identical experiments are conducted in a normal gravitational environment. The motion in that case is due to natural convection. The ratio of surface-tension to buoyancy forces in the tests is of the order of 10⁴ at reduced gravity conditions and 0·13 under normal gravity. In each case a two way flow occurs throughout most of the liquid. Comparison of the results from the two types of experiments is made in order to indicate differences in the flow details.     

Ultrahigh molecular weight polyethylene as used in articular prostheses (a molecular weight distribution study)

Currently there is widespread use of ultrahigh molecular weight polyethylene (UHMWPE) acetabular components in total joint replacement prostheses. What has been most surprising about the wear of UHMWPE under such circumstances is the occurrence of brittle fracture. Such fracture had not been observed in the usual engineering tests done in the laboratory on UHMWPE. It was only when prosthese which had been removed from patients were examined or run in hip joint simulators with serum or synovial fluid as the lubricant, that brittle fracture was encountered. The problem of environment-enhanced brittle fracture in plastics dates back to 1946. Interestingly, the phenomenon was first described in polyethylene. The prime variables involved are polymer molecular weight, sensitizing environment, stress filed, and temperature. Other things being equal, brittle behavior in polyethylene is extremely sensitive to the amount of low molecular weight polymer present. In the light of the foregoing we have studied the molecular weight distribution in six commercially available UHMWPE components. These were obtained from six different manufacturers. The specimens were characterized both on their bearing (wear) surfaces and in their interior bulk. The results obtained indicate that:

• 1 The UHMWPE components contain substantial amounts of low molecular weight polymer.
• 2 The UHMWPE components differ significantly in molecular weight distribution.
• 3 The UHMWPE components contain substantial amounts of crosslinked polymer.