No abstract available

[en] The density of He adsorbed in Vycor porous glass (pore diameter 70 A) at saturation vapour pressure is appreciably greater than that of bulk liquid. This has been interpreted in terms of a statistical layer model, in which the first layer has solid density, and the interparticle spacing in the second layer is that of bulk liquid at about 30 bar. It might be expected that if a specimen of Vycor porous glass is immersed in liquid ³He, application of quite moderate pressure will localize the second layer, accompanied by Pomeranchuk cooling if the process is isentropic. It is concluded from the observations that (i) the formation of solid in the adsorbed ³He film on Vycor at 100 mK and below does not take place until much higher pressure than that calculated from bulk properties, in disagreement with the interpretation of experiments at higher temperature with ⁴He on grafoil; (ii) the change in molar volume on solidification is twice as large as that of bulk; (iii) the proposed cooling method has more limited use than expected, but can be operated within about 10 psi of the melting curve, and can also be used as a two-stage Pomeranchuk refrigerator, in which the second stage starts at lower temperature when bulk solid is formed. (Kobatake, H

[en] This document provides a general introduction to biotechnology, bioproducts and alternatives to fossil fuels and petrochemicals. It includes an introduction to the concept of bioproducts, a description of common products that can be manufactured using biomass and an overview of the ways bioproducts are made. It also addresses issues such as risks and benefits of bioproduct technologies and the environmental, social and economic considerations of bioproducts. The possibilities of using biofuels and bioenergy for heat and power, to fuel vehicles and as a fuel for fuel cells were also discussed. Biogas from municipal and farm wastes is currently used to drive some gas turbines for power generation. The role of biochemicals and biomaterials in industrial processes and products was also reviewed along with some domestic and international bioproducts already developed and innovative products under development. The document also explains how plants, animals and other organisms can be used to replace or complement fossil fuels to help generate energy and make chemicals, plastics and other materials. While some reports suggest that bioproducts consume less energy and produce less greenhouse gases than conventional products, other reports suggest that they are rarely superior to conventional products and some may even contribute to the eutrophication of lakes, rivers and other surface waters. figs., 80 refs

[en] The topics raised in the discussion covered: the accuracy of the cost estimates for the project; the number of sluices to be used; factors controlling the selection of steel or concrete for caisson construction and the design life of the caissons; the type of gates and lock mechanism; shipping traffic forecasts; and the effect of the barrage on port operations. Separate abstracts have been prepared for the two papers under discussion. (UK)

[en] Objective: Low oxygen tension in the tumor microenvironment may have an important role during tumor growth, and is of particular prognostic significance in human cervical carcinoma. Because some human papillomavirus (HPV) infections are associated with cervical neoplasia, the relationship between hypoxia and apoptosis in primary cervical epithelial cells containing HPV16 E6 and E7, intact HPV 16 genome, and HPV positive cervical carcinoma cell lines, was examined. In addition, the relationship between hypoxia and apoptosis in spontaneous human cervical carcinomas was determined in situ. Materials and Methods: Primary normal human cervical epithelial cells were infected with retroviral vectors containing HPV16 E6 and E7 or transfected with a plasmid containing the whole HPV 16 genome. Clones were selected in neomycin containing medium. Exponentially growing cells were incubated under aerobic conditions (20% O₂), anaerobic conditions (0.02% O₂), or irradiated with 6 Gy. Analysis of apoptotic cells was performed by staining with Hoechst dye and propidium iodide and viewing with a fluorescent microscope. To determine the level of expression of the apoptotic modulators p53 and Bax, immunoblots were performed on whole cell extracts from treated cells. A clinical tumor hypoxia study was conducted at the University of North Carolina utilizing pimonidazole, a 2-nitroimidazole compound which binds irreversibly to cellular macromolecules under low oxygen conditions. Nine patients were enrolled with biopsy proven squamous cell carcinoma of the cervix and no prior treatment. Biopsies of the gross tumor were obtained after pimonidazole infusion. Contiguous histological sections were analyzed for hypoxia using a immunohistochemical technique and for apoptosis using TUNEL. Results: In vitro, hypoxia uncoupled p53 from E6 mediated degradation, and stimulated both p53 induction and apoptosis in primary cervical epithelial cells infected with the HPV E6 and E7 genes. In contrast, ionizing radiation did not stimulate p53 accumulation or apoptosis in these cells. Cervical epithelial cells containing the intact HPV 16 genome also exhibited hypoxia induced apoptosis. Hypoxia stimulated p53 induction but not apoptosis in cell lines derived from human cervical squamous cell carcinomas, indicating that these cell lines have acquired further genetic alterations independent of p53 which reduced their apoptotic sensitivity to hypoxia. Furthermore, E6 and E7 infected cervical epithelial cells subjected to multiple rounds of hypoxia followed by aerobic recovery achieved resistance to hypoxia induced apoptosis, indicating that hypoxia could directly select for cells with diminished apoptotic sensitivity. In situ, hypoxia and apoptosis were found to co-localize in tumors of patients with advanced clinical stage. Conclusion: Expression of viral oncoproteins in human cervical epithelial cells can increase their sensitivity to hypoxia-induced apoptosis. Hypoxia can select for variants that have lost their apoptotic potential and hypoxia correlates spatially with apoptosis in human cervical carcinoma biopsies. Therefore, these results implicate a role for hypoxia-mediated selection in human tumor progression and can in part explain the aggressiveness of cervical carcinomas with low p0₂ values

[en] We studied the reaction 12C(e,e'p) in quasielastic kinematics at momentum transfers between 0.6 and 1.8 (GeV/c)² covering the single-particle region. From this the nuclear transparency factors are extracted using two methods. The results are compared to theoretical predictions obtained using a generalization of Glauber theory described in this paper. Furthermore, the momentum distribution in the region of the 1s-state up to momenta of 300 MeV/c is obtained from the data and compared to the Correlated Basis Function theory and the Independent-Particle Shell model

[en] Separated longitudinal and transverse structure functions for the reaction 1H(e,eprime pi+)n were measured in the momentum transfer region Q2=0.6-1.6 (GeV/c)**2 at a value of the invariant mass W=1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parameterization fitted to very low Q2 elastic data

[en] The coherent 3He(e,eπ+)3H reaction was measured at Q2 = 0.4 (GeV/c)2 and W = 1.6 GeV for two values of the virtual photon polarization, ε, allowing the separation of longitudinal and transverse cross sections. The results from the coherent process on 3He were compared to H(e,eπ+)n data taken at the same kinematics. This marks the first direct comparison of these processes. At these kinematics (pπ = 1.1 GeV/c), pion rescattering from the spectator nucleons in the 3He(e,eπ+)3H process is expected to be small, simplifying the comparison to π+ production from the free proton

[en] The quasielastic (e,e[prime]p) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer Q2 of 8.1 (GeV/c)2. A nuclear transparency was determined by comparing the data to calculations in the plane-wave impulse approximation. The dependence of the nuclear transparency on Q2 and the mass number A was investigated in a search for the onset of the color transparency phenomenon. We find no evidence for the onset of color transparency within our range of Q2. A fit to the world's nuclear transparency data reflects the energy dependence of the free-proton-nucleon cross section

[en] The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at theta_cm = 37^o are consistent with the constituent counting rules for E_gamma∼> 4 GeV, while those at 70^o are consistent with the constituent counting rules for E_gamma ∼> 1.5 GeV