Multiphoton Ionization of Uracil at 355 nm

We present the experimental results from ionization and dissociation by multiphoton absorption (MPI) of uracil and a mixture of uracil with Ar using a Reflectron time of flight spectrometer along with radiation from 355 nm at pulsed Nd:YAG laser . We focus on the light ions production. The MPI mass spectra show that the presence and intensity of the resulting ions depend on the density power of the laser. The resulting ions in the mass spectra are identified and found similar behavior in the case of H+ and C+ as when multiple charged ions are used. Different results were found in contrast with those, recently reported, when electrons or photons of other wavelength were used. The number of 355nm absorbed photons was calculated accordingly to Keldysh theory and similar results were fond using pure uracil or uracil-Ar mixture. Our results are compared with those obtained in other laboratories under different experimental conditions, some of them show only partial agreement and differences are discussed

Expression of a barley cystatin gene in maize enhances resistance against phytophagous mites by altering their cysteine-proteases

Phytocystatins are inhibitors of cysteine-proteases from plants putatively involved in plant defence based on their capability of inhibit heterologous enzymes. We have previously characterised the whole cystatin gene family members from barley (HvCPI-1 to HvCPI-13). The aim of this study was to assess the effects of barley cystatins on two phytophagous spider mites, Tetranychus urticae and Brevipalpus chilensis. The determination of proteolytic activity profile in both mite species showed the presence of the cysteine-proteases, putative targets of cystatins, among other enzymatic activities. All barley cystatins, except HvCPI-1 and HvCPI-7, inhibited in vitro mite cathepsin L- and/or cathepsin B-like activities, HvCPI-6 being the strongest inhibitor for both mite species. Transgenic maize plants expressing HvCPI-6 protein were generated and the functional integrity of the cystatin transgene was confirmed by in vitro inhibitory effect observed against T. urticae and B. chilensis protein extracts. Feeding experiments impaired on transgenic lines performed with T. urticae impaired mite development and reproductive performance. Besides, a significant reduction of cathepsin L-like and/or cathepsin B-like activities was observed when the spider mite fed on maize plants expressing HvCPI-6 cystatin. These findings reveal the potential of barley cystatins as acaricide proteins to protect plants against two important mite pests

πNN\pi NN coupling determined beyond the chiral limit

Within the conventional QCD sum rules, we calculate the $\pi NN$ coupling constant, $g_{\pi N}$, beyond the chiral limit using two-point correlation function with a pion. We consider the Dirac structure, $i\gamma_5$, at $m_\pi^2$ order, which has clear dependence on the PS and PV coupling schemes for the pion-nucleon interactions. For a consistent treatment of the sum rule, we include the linear terms in quark mass as they constitute the same chiral order as $m_\pi^2$. Using the PS coupling scheme for the pion-nucleon interaction, we obtain $g_{\pi N}=13.3\pm 1.2$, which is very close to the empirical $\pi NN$ coupling. This demonstrates that going beyond the chiral limit is crucial in determining the coupling and the pseudoscalar coupling scheme is preferable from the QCD point of view.Comment: 8 pages, revtex, some errors are corrected, substantially revise

Reticulocyte Maturation Parameters Are Reliable Early Predictors of Hematopoietic Engraftment after Allogeneic Stem Cell Transplantation

AbstractEarly detection of donor-derived hematopoietic restoration after allogeneic stem cell transplantation (allo-SCT) is a crucial issue in the management of heavily immunocompromised patients. The aim of this prospective study was to validate our previously defined cutoff values for reticulocyte maturation parameters as early predictors of hematopoietic engraftment. Importantly, the effect of clinical variables in reticulocyte engraftment was also sought. For this purpose, we prospectively studied 136 consecutive patients undergoing allo-SCT from related (n = 89) or unrelated (n = 47) donors. High fluorescence reticulocytes (RETH), immature reticulocyte fraction (IRF), mean fluorescence index (MFI), and mean reticulocyte volume (MRV) were automatically measured in peripheral blood samples drawn on a daily basis. We previously defined reticulocyte engraftment when MFI ≥10, RETH ≥3%, IRF ≥10%, and MRV ≥110 fL. Median neutrophil engraftment was 18 days (range, 10-35 days); for reticulocyte parameters, the values were 14 days for IRF (range, 7-45 days), 14 days for MFI (range, 7-43 days), 15 days for RETH (range, 7-43 days), and 21 days for MRV (range, 9-74 days). These differences reached statistical significance for MFI and IRF when compared with standard neutrophil recovery, even when analyzing siblings or unrelated donors separately. In univariate analysis, donor-recipient ABO disparity adversely influenced erythroid engraftment (P = .04 for IRF, P = .03 for MFI), but the infusion of >2.9 × 106/kg of CD34+ cells was associated with a shorter time to reach erythroid engraftment (P = .02 for IRF and MFI). In Cox regression analysis, ≥100/μL neutrophils and IRF ≥10% were predictive parameters for standard neutrophil engraftment. Based on these findings, we suggest that serial measurement of IRF or MFI should be routinely used to trace hematopoietic restoration after allo-SCT because these preceded standard neutrophil recovery by a median of 4 days and are therefore very useful to make clinical decisions

Neolignanos en hojas de virola calophylla (warb)*

De las hojas de Virola Calophylla (Mynsticaceae) se aislaron e identificaron dos neolignanos nuevos, calophyn y calophyllin, y dos neolignanos conocidos, ácido meso-dihidroguaiarético y austrobailignano-6. Las estructuras fueron establecidas por métodos espectroscópicos

High-temperature phase transitions in dense germanium.

Through a series of high-pressure x-ray diffraction experiments combined with in situ laser heating, we explore the pressure-temperature phase diagram of germanium (Ge) at pressures up to 110 GPa and temperatures exceeding 3000 K. In the pressure range of 64-90 GPa, we observe orthorhombic Ge-IV transforming above 1500 K to a previously unobserved high-temperature phase, which we denote as Ge-VIII. This high-temperature phase is characterized by a tetragonal crystal structure, space group I4/mmm. Density functional theory simulations confirm that Ge-IV becomes unstable at high temperatures and that Ge-VIII is highly competitive and dynamically stable at these conditions. The existence of Ge-VIII has profound implications for the pressure-temperature phase diagram, with melting conditions increasing to much higher temperatures than previous extrapolations would imply