CdSe quantum dots using polyselenide precursor in soft chemical conditions

CdSe quantum dots were prepared by a simple microemulsion templating technique at low temperature and using common inorganic precursors. Size control was obtained by small variations in reactant concentrations. The chalcogenide source was a polyselenide solution. Narrow (30-40nm fwhm) band gap photoluminescence low defect level and high quantum yield were obtained.FCT and FEDER for financial support to the Research Centre, CFUM [PEst-C/FIS/UI0607/2011 (F-COMP-01-0124-FEDER-022711)] and to the research project PTDC/FIS/113199/200

Follicular dynamics in Serrana goats

Twenty-two Serrana goats were studied through two successive estrous cycles in order to characterize their follicular dynamics during the breeding season. The ovaries of the goats were scanned daily by realtime ultrasonography and all follicles ≥3mm were measured and classified. The data were classified by the number of follicular waves per goat to test the hypothesis that temporal and morphological differences between the last follicular wave of an ovary, irrespective of ovulation, will affect the selection of the next ovulatory wave. The mean interovulatory interval was 20.7±1.0 days (mean±S.D.). Three to five waves per estrous cycle were observed and 61.3% (19/31) of cycles had fourwaves. In estrous cycles with fourwaves, the day of onset of the first, second, third and fourth wave was 1.4±1.0, 6.9±1.4, 11.6±1.8 and 16.8±1.6, respectively. No differences (P > 0.05) were found between the day of onset of the first and second waves for estrous cycles with three, four or five waves. However, the day of onset of the third and fourth waves occurred later when the number of waves per estrous cycle increased (P < 0.001). The duration of the interwave interval (time between the day of onset of two consecutive waves) was longer when the second wave was ovulatory. The length of the growth phase (2.4±0.9 days) and size (5.9±0.7 mm) of the dominant follicle in the second wave were lower (P < 0.01) than for the first wave (3.3±1.2 days and 6.6±0.9 mm, respectively) and the fifth wave (4.1±1.2 days and 7.5±1.0 mm, respectively). Within pairs of ovaries, the onset of the last wave occurred later (P < 0.05) and was less variable in ovulatory ovaries (day 16.8±1.4, n = 20) than in anovulatory ovaries (day 15.1±3.7, n = 20). The length of the growing phase was longer (P < 0.001) in the last waves of ovulatory ovaries (3.1±0.9 days) than in the last waves of anovulatory ovaries (1.7±0.8 days). These results support the hypothesis that the day of onset of the ovulatory wave is related to or, at least, conditioned by the luteolysis and the decrease in plasma progesterone. In summary, the estrous cycle of Serrana goats is characterized by sequential follicular wave growth with a great variability in their onset and duration, with the exception of the ovulatory wave. The temporal and morphological differences observed in the last wave of estrous cycle provide strong evidence for the role of progesterone in their regulation

Perioperative donor bone marrow infusion augments chimerism in heart and lung transplant recipients

Background.: We and others have demonstrated that a low level of donor cell chimerism was present for years after transplantation in tissues and peripheral blood of heart and lung recipients; it was associated, in the latter, with a lower incidence of chronic rejection. To augment this phenomenon, we initiated a trial combining simultaneous infusion of donor bone marrow with heart or lung allotransplantation. Methods.: Between September 1993 and January 1995, 15 nonconditioned patients received either heart (n = 10) or lung (n = 5) allografts concurrently with an infusion of unmodified donor bone marrow (3.0 × 108 cells/kg), and were maintained on an immunosuppressive regimen consisting of tacrolimus and steroids. Results.: There was no complication associated with the infusion of donor bone marrow. Chimerism was detectable in 73% of bone marrow-augmented patients up to the last sample tested. Of the 5 control recipients who did not receive bone marrow infusion, only 1 had detectable chimerism by flow on postoperative day 15, which dwindled to an undetectable level by postoperative day 36. None of the patients had evidence of donor-specific immune modulation by mixed lymphocyte reaction. Conclusions.: The combined infusion of donor bone marrow and heart or lung transplantation, without preconditioning of the recipient, is safe and is associated with an augmentation of donor cell chimerism. © 1995 The Society of Thoracic Surgeons

Application of plateau value to predict fatigue life

Fatigue resistance of asphalt mixtures represents an important parameter for pavement design. This fatigue resistance is calculated through laboratory tests which require some time depending on the strain level applied to the specimen. For very low strain levels, identical to the one installed in the pavement, one test may last more than one week depending on the testing frequency. The time needed for the development of the fatigue law may last long-er. Recent developments introduced an energy approach, based on the ratio of dissipated energy change, which leads to a plateau value that requires short testing to predict the specimen failure. This paper presents the implementation of this approach to evaluate the fatigue resistance of Portuguese asphalt mixtures. Three asphalt mixtures were studied. The first mixture was tested using two strain levels and three specimens for strain level. The second mixture was tested using three strain levels and three specimens per strain level, whereas the last mixture was tested with 18 specimens, 6 per strain level. The approach seems to have potential to be used for fast evalu-ation of the fatigue response of asphalt mixtures

The prediction of fatigue life using the k1-k2 relationship

Fatigue resistance is used in the analysis and design of pavements to predict their life cycle. It is evaluated through time consuming laboratory tests, mainly when performed at very low strain levels. At low strain levels the testing time can last more than one day. Due to the heterogeneity of the material, a large number of samples are tested during days or weeks. The results of fatigue tests are expressed in terms of the number of cycles for the tensile strain level applied. Two constants (k1 and k2) obtained from a statistical analysis take part in this rela-tionship. To know these two constants, at least two fatigue tests are needed, performed at differ-ent strain levels. k1 and k2 can be correlated and, in this case, the relationship between the fati-gue life and the strain level has only one constant, which can be evaluated using the results obtained by a fatigue test. This paper presents the evaluation of the k1 and k2 relationship for Portuguese mixtures based on the results of 32 different asphalt mixtures composed by four dif-ferent types of aggregate gradations

Exploring multiple eco-routing guidance strategies in a commuting corridor

The introduction of eco-routing systems has been suggested as a promising strategy to reduce carbon dioxide emissions and criteria pollutants. The objective of this study is to scrutinize the impacts of an eco-routing guidance system on emissions through the use of a case study in a commuting corridor. This research aims at assessing the potential environmental benefits in terms of different pollutant emissions. Simultaneously, it addresses the extent of variations in system travel time that each eco-routing strategy implies. The methodology consists of three distinct phases. The first phase corresponded to the adjustment of a micro simulation platform of traffic and emissions with empirical data previously collected. Secondly, volume-emission-functions (VEF) were developed based on the integrated modelling structure. Finally, different scenarios of traffic flow optimization were performed at the network level based on a simplified assignment procedure. The results show that if the traffic assignment is performed with the objective of minimize overall impacts, total system environmental damage costs can be reduced up to 9% with marginal oscillations in total system travel time. However, if drivers are advised based on their own emissions minimization, total system emissions may be higher than under the standard user equilibrium flow pattern. Specifically, environmentally friendly navigation algorithms focused on individual goals may tend to do divert traffic to roads with less capacity affecting the performance of the remaining traffic. This case study brings new insights about the difficulties and potentials of implementing such systems