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The main problems of establishment a slow growth in vitro collection of citrus and other tree crops cultivars are high degree of fungal contamination of bud explants and low growth potential of shoots. In this regard, the aim of current research is to assess the efficiency of decontamination procedure and the possibility of tissue culture initiation and slow growth conservation of valuable lemon cultivars. The best results of surface sterilization were obtained using immersion solutions of 0.3 % Veltolen – 25 minutes or 10 % Domestos – 25–30 minutes. In these treatments, 27.7–33.0 % of aseptic explants were obtained, respectively. However, after the third subculture, the yield of aseptic viable explants decreased till 10 % as a result of secondary contamination by endophytic fungi. The addition of biocide (“Gavrish”) in a nutrient medium at a concentration of 1 ml/l helped to increase the yield of aseptic viable explants till 50 %. However, after the third subculture the photosynthetic activity and the pigments content as well as growth rate decreased. Plants dropped yellowish leaves and eventually died. Thus, 37.35 % of plantlets survived after 8 months of conservation, and only 14.6 % survived after 10 months. Even after the third month of conservation significant decrease in the viability index and the coefficient of photosynthetic activity occurred in plants. Chlorophyll a in leaves decreased from 1.59 to 1.14 mg/g during 12 months in vitro conservation. The similar tendency observed on clorophyll b and carotenoids content. The experiments were carried out for 5 years using different lemon cultivars and other citrus varieties and cultivars. Thus, micropropagation and slow growth in vitro conservation of valuable lemon cultivars are still problematic and requires new technical solutions due to the low growth potential of plantlets raised from the mature buds that is consistent with the data of other researchers.

Condensation removes water vapor molecules from the gas phase and reduces the weight of the air column. This disturbs hydrostatic equilibrium and makes air circulate under the action of the recently described evaporative force. Meesters, Dolman and Bruijnzeel (2009) criticized the physical bases of the new circulation driver with a major claim that the ascending air motions induced by the evaporative force should rapidly restore the hydrostatic equilibrium and become extinguished. Here we respond that in fact these air motions sustain the disequilibrium of air pressure through the reduction of the weight of the air column via condensation that continuously occurs as the ascending moist air cools. In the traditional meteorological paradigm condensation is primarily considered in terms of the effect it has, via latent heat release, on air density, while its immediate effect on the weight of air column is not accounted for. The critique of Meesters et al. is therefore informative in highlighting the traditional lines of thought that should be re-visited to incorporate the new physical knowledge. Such an effort is arguably worthy of undertaking as the evaporative force concept bears tangible potential for solving some of the key problems that are challenging modern atmospheric science.

Complete fusion (CF) and incomplete fusion (ICF) reactions were studied for the cases of the loosely bound 6He and 6Li projectiles bombarding 166Er and 165Ho targets at energy of about 10 MeV/nucleon. Experiments were carried out to test an approach exploiting the measured intensities of γ rays emitted at the transitions between the yrast-band levels of reaction products formed after the termination of neutron evaporation. Partial waves feeding the CF reactions 165Ho (6Li, 5 n) 166Yb and 166Er(6He, 6 n) 166Yb as well as ICF 165Ho (6Li, α3n) 164Er and 166Er(6He, α4n) 164Er reaction channels were revealed from the obtained γ-ray data. The method of exit channel identification via the triple coincidence (γ1-γ2-light charged particle) was employed for these reactions study. (c) 2012: Pleiades Publishing, Ltd.

By using the 1H(6Li,6Be)n charge-exchange reaction, continuum states in 6Be were populated up to E_t=16 MeV, E_t being the 6Be energy above its three-body decay threshold. In kinematically complete measurements performed by detecting alpha+p+p coincidences, an E_t spectrum of high statistics was obtained, containing approximately ~5x10^6 events. The spectrum provides detailed correlation information about the well-known 0^+ ground state of 6Be at E_t=1.37 MeV and its 2^+ state at E_t=3.05 MeV. Moreover, a broad structure extending from 4 to 16 MeV was observed. It contains negative parity states populated by Delta L=1 angular momentum transfer without other significant contributions. This structure can be interpreted as a novel phenomenon, i.e. the isovector soft dipole mode associated with the 6Li ground state. The population of this mode in the charge-exchange reaction is a dominant phenomenon for this reaction, being responsible for about 60% of the cross section obtained in the measured energy range., 8 pages, 7 figures

Expérience à Dubna (RU); In our experiment we studied three body momentum correlations of 6He breakup products emitted in the quasifree knockout reaction 4He(6He, 2α) at 6He beam energy 25A MeV. For the first time a detailed study of nuclear structure was done in the reaction of quasifree scattering with an unbound system as a spectator. In the experiment we used a detection system of large angular acceptance allowing us to investigate the process in a wide range of kinematical parameters. It was shown that the data obtained in the experiment are well consistent with the predictions obtained with the use of the Plane Wave Impulse Approximation allowing for the final state interaction between the two spectator neutrons.

The low-lying spectrum of 8 He was studied in the 3 H( 6 He, p ) 8 He transfer reaction for small center of mass angles. The 0 + ground state (g.s.) of 8 He and excited states, 2 + at 3.6–3.9 MeV and (1 + ) at 5.3–5.5 MeV, were populated with cross sections of 200, 100–250, and 90–125 μ b/sr. Some evidence for the excited state at about 7.5 MeV can be found in the data. The possible nature of the near-threshold anomaly above 2.14 MeV in 8 He is related to the population of a 1 – continuum (soft dipole excitation) with a peak energy value at about 3 MeV. This assumption can probably resolve the problem of a large uncertainty existing in the experimental data on the 8 He 2 + state energy.

International audience; Complete fusion (CF) and incomplete fusion (ICF) reactions were studied with the beams of loosely bound 6He and 6Li bombarding 166Er and 165Ho targets. Experiments were carried out to test an approach exploiting the measured intensities of γ rays emitted at the transitions between the yrast‐band levels of reaction products formed after the termination of neutron evaporation. Partial waves feeding the CF [165Ho(6Li,5n)166Yb, 166Er(6He,6n)166Yb] and ICF [165Ho(6Li,α3n)164Er, and 166Er(6He,α4n)164Er] reaction channels were revealed from the obtained γ‐ray data. © 2009 American Institute of Physics

Low-energy spectra of the He-8,He-10 nuclei were investigated in the (t, p)-type reactions at small centre-of-mass angles using similar to 25AMeV beams of He-6 and He-8 nuclei. The 0(+) ground state (g.s.) of He-8 and excited states, 2(+) at 3.6-3.9MeV and (1(+)) at 5.3-5.5 MeV, were populated with cross-sections of 200, 100-250, and 90-125 mu b/sr, respectively. To account for a near-threshold anomaly observed in the He-8 spectrum the population of a 1(-) continuum (soft dipole excitation) was considered. The lowest-energy group of events in the He-10 spectrum was observed at similar to 3MeV with a cross-section of similar to 140 mu b/sr. This result is consistent with the previously reported observation of He-10 providing a new g.s. position for He-10 at about 3MeV.

The spectrum of $\rm ^He$ was studied by means of the $\rm ^He, p)^He$ reaction at a laboratory energy of 25 $\rm MeV/A$ and small center-of-mass angles. Missing mass spectrum of $\rm ^He$ was derived from the obtained p-8He coincidence. A resolution of 0.7 MeV was achieved in this spectrum for the measured $\rm ^He$ energy. Most likely, a well isolated group of 10 events detected between 2 and 5 MeV and showing a maximum at about 3 MeV in the spectrum of the present work exhibits the $\rm ^He$ g.s. resonance.

International audience; Detailed spectroscopic information of excited nuclear states in deformed transfermium nuclei is scarce. Most of the information available today has been obtained from investigations of fine structure $\alpha$ decay. Although $\alpha$ decay gives access to hindrance factors and lifetimes which are strongly correlated to shell/subshell closures and the presence of isomers, only the combined use of $\gamma$ and conversion electron spectroscopy allows the precise determination of excitation energy, spin and parity of nuclear levels. In particular, the study of odd isotopes gives crucial information on the single particle states available at and around the Fermi surface. In the following, the preliminary results of decay studies using $\alpha - \gamma$ and $\alpha - \beta$ coincidences at the focal plane of the VASSILISSA recoil separator are presented.

With the aid of the Geant4 Monte Carlo simulation package a new detection system has been designed for the focal plane of the recoil separator VASSILISSA situated at the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. GABRIELA (Gamma Alpha Beta Recoil Investigations with the Electromagnetic Analyser VASSILISSA) has been optimised to detect the arrival of reaction products and their subsequent radioactive decays involving the emission of alpha- and beta-particles, fission fragments, gamma- and X-rays, and conversion electrons. The new detector system is described and the results of the first commissioning experiments are presented., 24 pages, Submitted to NIM A

A comparative analysis of the physical foundations of tomography based on transmitted and scattered X-rays is presented. Comparative estimates of the effects of the object’s features, radiation parameters, and measurement schemes on the main characteristics of reconstruction and measurement results are presented. These estimates reveal the common and directly opposite effects in the tomography techniques based on transmitted and scattered X-rays.

International audience; Convection reduces greenhouse effect by transporting a certain amount of non-radiative dynamic energy to the upper atmosphere, where this energy dissipates and radiates into space without interaction with greenhouse substances in the lower atmosphere. In this paper we show that the height of the convective layer zc is finite and independent of atmospheric optical thickness ?s at large values of the latter. We derive an analytical formula for zc at large values of ?s for condensable and non-condensable greenhouse substances. The formula obtained yields reasonable quantitative estimates of the observed height of convective layer on Venus and at low latitudes on Earth, where atmospheric thickness of water vapor is maximum. The dissipative power of dynamic convective processes is limited by the incoming flux of solar radiation. Height of convective layer being finite, values of optical depth at the top of the convective layer and at the mean height of convective energy dissipation increase proportionally to the atmospheric optical thickness, while the contribution of convective energy fluxes to formation of the outgoing flux of thermal radiation proportionally diminishes. As far as optical thickness of condensable greenhouse substances grows exponentially with increasing surface temperature, the obtained results lead to the conclusion that the outgoing thermal radiation into space in the presence of convection tends exponentially to zero with increasing surface temperature, instead of reaching a finite plateau as suggested by earlier radiative-convective studies.

Resonance states of 5H were investigated through the two-neutron transfer reaction t(t, p)5 H. A triton beam at 57.5 MeV and a cryogenic liquid tritium target were used. The 5H missing mass spectrum in triple coincidence, proton + triton + neutron, shows a resonance at 1.8 ± 0.1 MeV above the t + 2n decay threshold. This energy is in good agreement with the result reported in Phys. Rev. Lett. 87 (2001) 092501. The resonance width, Γintr ≤ 0.5 MeV, is surprisingly small and difficult to reconcile with theory predictions. © 2003 Published by Elsevier B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

Due to the exponential positive feedback between sea surface temperature and saturated water vapour concentration, dependence of the planetary greenhouse effect on atmospheric water content is critical for stability of a climate with extensive liquid hydrosphere. In this paper on the basis of the law of energy conservation we develop a simple physically transparent approach to description of radiative transfer in an atmosphere containing greenhouse substances. It is shown that the analytical solution of the equation thus derived coincides with the exact solution of the well-known radiative transfer equation to the accuracy of 20% for all values of atmospheric optical depth. The derived equation makes it possible to easily take into account the non-radiative thermal fluxes (convection and latent heat) and obtain an analytical dependence of the greenhouse effect on atmospheric concentrations of a set of greenhouse substances with arbitrary absorption intervals. The established dependence is used to analyse stability of the modern climate of Earth. It is shown that the modern value of global mean surface temperature, which corresponds to the liquid state of the terrestrial hydrosphere, is physically unstable. The observed stability of modern climate over geological timescales is therefore likely to be due to dynamic singularities in the physical temperature-dependent behaviour of the greenhouse effect. We hypothesise that such singularities may appear due to controlling functioning of the natural global biota and discuss major arguments in support of this conclusion.

An environmentally safe liquid/solid tritium target suitable for beams of radioactive nuclei was created and used in the study of t+d and t+t transfer reactions with putting emphasis on the observation of 4H and 5H resonance states. A state of 4H with Eres=3.22±0.15 MeV and Γobs=3.33±0.25 MeV was obtained in t+d reaction from the spectra of protons leaving the target at θlab=18°–32° and detected in coincidence with tritons. A valuable fraction of protons detected in t+t reaction at θlab=18°–32° in ptn coincidence events was attributed to the states of 5H nucleus. At ∼2.5 MeV above the tnn decay threshold the 5H spectrum shows up a narrow maximum followed by a wide structure at 4–7 MeV. One can not exclude that interference effects could modify the observed 5H resonance maximum resulting in its energy shift and width reduction.

Angular distributions for elastic scattering and 1n and 2n transfer reactions were measured for the 6 He + 1 H system at 25 MeV/nucleon. The experimental data were analyzed in the framework of the one-step finite range DWBA model. The results suggest a lower triton spectroscopic amplitude for the 6 He nucleus as compared to the shell model calculation.