Influence of temperature and substrate concentration on bacterial growth yield in Seine River water batch cultures

The growth of natural bacterial assemblages was monitored in 3-liter reactors under various temperature and substrate concentration conditions. The oxygen concentration was continuously monitored, and subsamples were taken at short time intervals to determine bacterial number and biomass. The rate of bacterial mortality was also determined. Bacterial growth yield was calculated as the ratio of net production (increase in biomass corrected for mortality) to gross production (net production plus oxygen consumption expressed in carbon units). Averaging 33%, the growth yield did not show any trend with temperatures in the range of 8 to 25 degrees C but increased with the concentration of dissolved organic carbon in the range of 2 to 12 mg of C.liter-1.     

Insight into signal transduction: structural alterations in transmembrane helices probed by multi-1 ns molecular dynamics simulations

The hypothesis of structural alteration in transmembrane helices for signal transduction process is viewed by molecular dynamics simulation techniques. For the c-erbB-2 transmembrane domain involved in oncogenicity, the occurrence of conformational changes has been previously described as transition from the alpha to pi helix. This dynamical feature is thoroughly analyzed for the wild phenotype and oncogenic sequences from a series of 18 simulations carried out on one nanosecond time scale. We show that these structural events do not depend upon the conditions of simulations like force field or starting helix coordinates. We demonstrate that the oncogenic mutations Val659 Glu, Gln and Asp do not prevent the transition. Furthermore, we show that beta branched residues, in conjunction with Gly residues in the c-erbB-2 sequence, act as destabilizers for the alpha helix structure, pi deformations are tightly related to other local structural motifs found in soluble and membrane proteins. These structural alterations are discussed in term of structure-activity relationships for the c-erbB-2 activating mechanism mediated by transmembrane domain dimerization.     

Détermination du coefficient d'écoulement des gravillons

The angularity of aggregates of alluvial origin is a subject that systematically arises when one touches upon problems of intergranular friction in pavement courses and making concrete. The authors describe a test, based on measurement of the flow time of the material which tends to quantify this parameter. In particular, this test permits to determine the “indice de concassage” of the material without knowing the conditions of its elaboration and the real granularity of the material before crushing. Realization of measures and behaviour investigation of composite materials should make it possible to establish quickly new specifications in this field.     

Treatment of severe social phobia: Effects of guided exposure with and without cognitive restructuring.

Fifty-one social phobics with severe scrutiny fears were randomly assigned to treatment in an experiment designed to assess the effectiveness of therapist-guided exposure and to determine the extent to which cognitive restructuring alone increases the effects of this exposure. Additionally, the ability of treatment-induced changes in locus of control, of irrational attitudes, and of within-session habituation to predict level of functioning at follow-up was assessed. Treatment integrity assessment showed compliance with instructions that was consistent with the respective treatments. The combined condition proved to be significantly more effective than guided exposure alone in endstate functioning, in increasing behavioral approach, and in decreasing self-rated avoidance. Regression analysis showed that treatment-induced changes in fear of negative evaluation (FNE), irrational beliefs, locus of control, and exposure-practice habituation were significantly predictive of endstate functioning at follow-up; the change in FNE accounted for virtually all the explained variance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structure cristalline de la phase haute temperature de PbSO4.2PbO A 973K

Full profile X-ray powder diffraction structure refinements have been performed on the two polymorphs of the PbSO₄.2PbO phase. Both structures can be described as infinite double-chains of edge-sharing OPb₄ tetrahedra linked by the sulfate groups and running parallel to the (010) direction for the low temperature phase, and parallel to the (001) direction for the high temperature one. The mechanism of the phase transition may be described as a rotation of the sulfate group about one of its pseudo-ternary axis. The space group adopted for the refinement of the structure of the high temperature phase is Cmcm.     

Introduction to the special section on structural analysis of social behavior.

The structural analysis of social behavior (SASB) model dissects interpersonal and intrapsychic events into 3 underlying dimensions: (a) focus (on other, on self with other, and on self with self); (b) affiliation (love vs. hate); and (c), interdependence (enmeshment or dominance–submission vs. differentiation or emancipate–separate). Accompanied by predictive principles (similarity, opposition, complementarity, introjection, antithesis), the model can operationalize important aspects of a wide range of psychological events. Questionnaires, coding systems, and software permit the SASB model to be applied in a wide array of clinical and research contexts. It has been used by people of divergent theoretical persuasions including the interpersonal, cognitive-behavioral, client-centered, psychoanalytic, expressive, family, and group approaches. In this article, the model and its predictive principles are reviewed, along with examples of research, clinical, and theoretical applications. The articles in this section provide examples of especially creative and appropriate uses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Etude des phases ferroelastiques de Pb3V2O8 : Determination de la maille cristalline de la phase α ferroelectrique basse temperature

The cell parameters of the ferroelastic and ferroelectric phase of Pb₃V₂O₈ (T < 262 K) have been determined by very accurate X-ray powder diffractometry ; at 77 K, $\text{a}\text{= 7.460 (1)}\text{A}\text{?}$, $\text{b}\text{= 6.191 (1)}\text{A}\text{?}$, $\text{c}\text{= 9.348 (1)}\text{A}\text{?}$ and $\text{β = 116.63 (1)}\text{A}\text{?}$. This monoclinic cell is characterized by Z = 2 and the space group is A2. Thermal expansion tensors have been measured versus temperature for the three phases α (T < 262K), β (262K < T < 360 K) and γ (T > 360 K). The intermediate phase β is characterized by an important thermal expansion anisotropy and its molecular volume is higher than that of the two other phases α and γ.     

Tritium-Labeled Compounds X. Isotope Effects in the Oxidation of Aldoses-1-t With Bromine

Tritium isotope effects have been used in bromine oxidation studies of aldoses to evaluate two reaction paths previously postulated by Isbell and Pigman, namely, direct oxidation and oxidation after anomerization. Because the former path involves a primary isotope effect (k*/k = 0.14, approximately) and the latter a secondary isotope effect (k*/k = 0.80, approximately) it was found possible to evaluate the relative importance of the two reaction paths from the overall isotope effects, which ranged from 0.20 to 0.59.Under the conditions reported, the direct oxidation for the axial anomers ranges from 38 percent for α-d-galactose to 94 percent for α-d-lyxose. Differences in the proportion of the anomer oxidized by each of the two paths are explained by variations in the free energy required for reaching the respective transition states. Aldoses of high conformational stability having an axial C1-hydroxyl group resist the change in conformation necessary for direct oxidation and react in large measure through a change in configuration (anomerization). Aldoses of lower conformational stability having an axial C1-hydroxyl group react largely through a change in conformation, because this path does not have a high energy barrier.The equatorial anomers of d-glucose-1-t and maltose-1-t showed isotope effects of 0.32 and 0.23, respectively in comparison with a value of 0.14 previously found for the oxidation of aldoses-1-t with iodine in alkaline solution. The isotope effect in the oxidation of d-glucose-1-t with d-glucose oxidase at 30 °C was found to be 0.15. These strong isotope effects are in accord with the rupture of the C1 to H bond in the rate-determining step.The following reactions gave the values for k*/k cited in parentheses: d-glucose-1-t +NaCN (0.83); d-glucose-1-C¹⁴ + NaCN (1.00); d-glucose-1-t+NaBH₄ (0.73); d-mannose-1-t + phenylhydrazine (0.83); and d-mannose-1-C¹⁴ + phenylhydrazine (0.95). The values of k*/k are typical of aldose reactions involving rate-determining isomerization of the pyranose structure.The isotope effects were measured by a double-label method and by a newly developed method based on the radioassay of water evolved in the reaction.     

Dielectric Breakdown of Porous MgAl2O4

The effects of controlled porosity on the dielectric breakdown of sintered MgAl₂O₄ were measured using an acoustic emission technique. Results are compared to a statistical model relating dielectric strength to a random distribution of spherical pores and the probability of pores aligned in a vertical column. Data are in good agreement with the model when only maximum pore size is considered .