Relationships between culturable soil microbial populations and gross nitrogen transformation processes in a clay loam soil across ecosystems

The size and quality of the soil organic matter (SOM) pool can vary between ecosystems and can affect many soil properties. The objectives of this study were to examine the relationship between gross N transformation rates and microbial populations and to investigate the role that SOM plays in these factors. In our study, culturable microbial and actinomycete populations were positively correlated with gross mineralization and ammonium (NH₄⁺) consumption rates over time in both ecosystems. These correlations provide evidence that microbial plate counts could be a good representation of all microbes responsible for gross mineralization and gross NH₄⁺ consumption. Rates of gross mineralization, nitrification and NH₄⁺ consumption were significantly greater in forest soil than old-field soil. These greater rates in forest soil could be due to the presence of higher levels of readily transferable substrates in SOM. Gross nitrification rates were considerably lower than gross mineralization and NH₄⁺ consumption rates over the experimental period, indicating heterotrophic uptake of NH₄⁺ rather than use by autotrophic nitrifiers under soil and environmental conditions in this study. Additionally, microbial populations were significantly (p<0.01) greater in forest soil than in old-field soil, which could also be related to the higher level of SOM in the forest soil. Net mineralization and nitrification rates were similar between ecosystems. Results also showed that net rates were highly correlated to each other, but were not correlated with culturable microbes or gross N transformation rates, indicating the isolation of net rates in relation to fundamental controlling factors.     

Medial calcinosis of M?nckeberg. A review of the problem and a description of a patient with involvement of peripheral, visceral and coronary arteries

Massive medial calcific deposits (M?nckeberg's calcinosis) are described in the peripheral and visceral arteries, and similar but small-sized deposits in the coronary arteries of a 41 year old woman with diabetes mellitus. Although observed by roentgenogram fairly commonly during life in the muscular arteries of the legs in middle-aged men, medial calcinosis infrequently involves the visceral arteries and has never, to our knowledge, been documented in the coronary arteries. Although it may be associated with intimal atherosclerosis, medial calcinosis, per se, does not obstruct the lumens of the arteries and, therefore, does not lead to symptoms or signs of limb or organ ischemia. The cause of medial calcinosis remains a mystery, but it appears to affect people with diabetes more frequently than those without.     

Growth of syngeneic transplantable tumors in Syrian hamsters immunized with hamster embryonic tissue

The effect of immunization of Syrian hamsters with the hamster embryonic tissue on the growth of two syngeneic transplantable tumours was studied. Immunization of the inbred hamsters with embryonic hamster tissue with subsequent transplantation to them of transplantable syngeneic tumours led neither to inhibition nor to enhancement of the tumour growth. It is suggested that the embryonic antigens do not participate in the formation of the transplantation antitumour immunity.     

Reduced collagen accumulation after major surgery

The preoperative and postoperative wound-healing capacity of 23 patients undergoing elective major abdominal, thoracic or urological surgery was tested objectively by the subcutaneous accumulation of hydroxyproline and proline in an expanded polytetrafluoroethylene (ePTFE) tube. Before scheduled surgery two ePTFE tubes were implanted for removal after 5 and 10 days. This was repeated for each patient immediately after surgery. After 10 days a higher amount of hydroxyproline was measured before than after operation (median 2.91 (range 0.37-14.45) versus 1.45 (range 0.26-6.94) micrograms/cm, P = 0.01)). This decline was significantly higher in the six patients who had a postoperative infection (median 3.02 (range -0.06 to 6.14) versus 0.36 (range -1.56 to 12.60) micrograms/cm, P = 0.02). This study shows that major surgery is associated with impairment of subcutaneous collagen accumulation in a test wound, suggesting diminished systemic wound-healing capacity in such patients.     

Crystallization and preliminary crystallographic analysis of an amylopullulanase from the hyperthermophilic archaeon Pyrococcus woesei

The thermostable amylopullulanase from Pyrococcus woesei was crystallized. Crystals, suitable for a crystallographic analysis up to a size of 0.6 mm in their longest dimension, have been obtained by the vapor diffusion method in a solution containing polyethyleneglycol 4000 (PEG 4000), isopropanol, and Tris/Cl- buffer pH 7.5. Crystals grown under these conditions form hexagonal rods and diffract to a maximum resolution of 3 A. The crystals belong to the trigonal lattice type with the spacegroup P3(1)21 or P3(2)21, respectively, have the cell dimensions a = b = 96.8 A, c = 196.2 A, alpha = beta = 90 degrees, gamma = 120 degrees. The crystals have a theoretical packing density of 2.7 A3/Da, assuming one molecule with a molecule weight of 88.8 kDa in the asymmetric unit. Furthermore the self-rotation analysis of the dataset revealed only crystallographic symmetries. The merged native data of two crystals resulted in a 88% complete dataset.     

Silvered-PMMA reflectors

Metallized, flexible polymeric reflector materials are much lighter and potentially less expensive than the conventional glass/metal mirrors often used in solar thermal concentrators such as heliostats and parabolic dishes and troughs. Unweathered silvered-PMMA reflectors have a solar reflectance at least as high as glass reflectors, but their environmental durability needs to be demonstrated. ECP-305, a silvered-PMMA film available commercially from the 3M Company and developed in collaboration with the National Renewable Energy Laboratory, is the current state of the art. Important progress has been made in overcoming the three primary mechanisms causing ECP-305 to lose reflectance. These mechanisms are: (1) photon-induced silver corrosion, (2) surface soiling, and (3) a form of delamination called tunneling. Given the progress in resolving these performance lifetime issues, silvered-PMMA films should meet the reflectance and durability goals.