Atomic-resolution electrochemistry with the atomic force microscope: copper deposition on gold

The atomic force microscope (AFM) was used to image an electrode surface at atomic resolution while the electrode was under potential control in a fluid electrolyte. A new level of subtlety was observed for each step of a complete electrochemical cycle that started with an Au(111) surface onto which bulk Cu was electrodeposited. The Cu was stripped down to an underpotential-deposited monolayer and finally returned to a bare Au(111) surface. The images revealed that the underpotential-deposited monolayer has different structures in different electrolytes. Specifically, for a perchloric acid electrolyte the Cu atoms are in a close-packed lattice with a spacing of 0.29 +/- 0.02 nanometer (nm). For a sulfate electrolyte they are in a more open lattice with a spacing of 0.49 +/- 0.02 nm. As the deposited Cu layer grew thicker, the Cu atoms converged to a (111)-oriented layer with a lattice spacing of 0.26 +/- 0.02 nm for both electrolytes. A terrace pattern was observed during dissolution of bulk Cu. Images were obtained of an atomically resolved Cu monolayer in one region and an atomically resolved Au substrate in another in which a 30 degrees rotation of the Cu monolayer lattice from the Au lattice is clearly visible.     

Interactions between different media and follicle‐stimulating hormone supplementation on in vitro culture of preantral follicles enclosed in ovarian tissue derived from collared peccaries (Pecari tajacu Linneaus, 1758)

The aim was to verify the effect of follicle‐stimulating hormone (FSH) supplementation to α‐MEM+ or TCM199+ media on the in vitro development of ovarian preantral follicles (PFs) derived from collared peccaries. Ovaries (n = 5 pairs) were collected and divided into fragments destined to control group (non‐cultured) or treatments that were cultured for 7 days. The PFs morphology, growth and activation were evaluated by classical histology. The immunohistochemistry markers Ag‐NOR and PCNA were used for nuclear proliferation analysis, and the picrosirius red labelling was used for ovarian extracellular matrix (ECM) evaluation. After 7‐day culture, only the TCM199+ treatment maintained the proportion of intact PFs similar to day 1 (63.2%), but no differences were found among treatments (p > .05). In addition, a significant increase in the growing follicles proportion was verified for all the treatments, indicating follicular activation (p > .05). By the Ag‐NOR analysis, only the TCM199+/FSH maintained the nuclear proliferation similar to the first day (p > .05). The picrosirius red staining revealed that the ECM remained intact in all the treatments (p > .05). We suggest the use of TCM199+ medium supplemented of FSH for the in vitro development of peccaries PFs under 7‐day culturing conditions.     

Durum wheat landraces from Syria

Syrian durum wheat landraces from diverse collection sites were evaluated for agronomic performance under arid conditions over two seasons at four locations, at two levels of nutrient availability.Grain yield differed considerably among locations. Within locations, significant population and fertilizer effects were demonstrated. In most cases, maximum yield was achieved by landraces, which demonstrates the breeding value of local germplasm. In a particular environment, the population effect was nonsignificant for total dry matter production, but significant for straw and grain yield. Nitrogen application was ineffective if moisture availability was the dominant growth limiting factor.Correlations between plant characteristics at evaluation and collection site characteristics were limited, and therefore, their utilization in germplasm evaluation appear limited. The negative relation between grain yield and soil nitrogen content at the collection site may be caused by the comparative disadvantage that germplasm from regions with favourable growing conditions has under low-yielding conditions.Particular environmental conditions at the collection site were no indicator for the response to changed growing conditions. Relatively high grain yields under good and adverse growing conditions excluded each other in all but two cases. Also, it was difficult to relate grain yield to regions of collection, as the response of individual landraces from a certain region to changing growing conditions differed strongly. Differentiation on the basis of landrace groups appears more promising. The Hauran landrace group provided the largest number of populations with relatively high grain yields over diverse environments.     

Transform-limited, narrow-linewidth lasing action in organic semiconductor microcavities

Lasing action in organic vertical-cavity surface-emitting laser (OVCSEL) structures is demonstrated. Optically pumped OVCSELs with an active layer composed of a thin-film organic semiconductor tris-(8-hydroxyquinoline) aluminum (Alq3) doped with DCM laser dye produced very narrow linewidth (0.2 +/- 0.1 angstrom), high-power (3 watts) emission that could be varied in different devices from orange to red. The efficient energy transfer from Alq3 to DCM results in a threshold input energy of 300 microjoules per square centimeter. An operational lifetime >10(6) laser pulses was achieved for a device operated well above threshold in atmosphere. The linewidths above threshold are Fourier transform-limited and could potentially be narrowed further.     

Tramadol plus metamizole combined or not with anti‐inflammatory drugs is clinically effective for moderate to severe chronic pain treatment in cancer patients

ObjectiveTo test the effectiveness and safety of tramadol plus metamizole combined or not with a non-steroidal anti-inflammatory drug (NSAID) for treating moderate to severe chronic neoplastic pain in dogs, and its impact on quality of life (QL).Study designProspective, uncontrolled, open-label, clinical study.AnimalsSixty nine client-owned dogs with multiple forms of cancer and visual analog scale (VAS) pain score ≥40 after receiving NSAIDs for at least 7 days.MethodsThe MN group received metamizole + NSAID, MNT group received metamizole + NSAID + tramadol and MT group received metamizole + tramadol. Pain was scored by the 0 to 100 mm VAS (0 = no pain, 100 = worst pain) and analgesic therapy was considered effective if 25 mm differences in VAS scores were observed between day 0 and the follow ups. The QL was evaluated according to a 0 to 36 scoring method for dogs (0 = worst, 36 = best) and side effects were recorded. Data were registered at day 0 (baseline) and at the first and second follow ups (7 and 14 days after day 0, respectively).ResultsThe MN group had less analgesia at day 7 (25%) and day 14 (42%) than MNT (59%, p = 0.0274; 76%, p = 0.0251, respectively) and MT groups (69%, p = 0.0151; 81%, p = 0.0341, respectively). The QL scores were lower in the MN group at the first (score 23) and second follow up (score 26) than in MNT (27, p = 0.0847; 30, p = 0.0002) and MT (28, p = 0.0384; 31, p = 0.0001) groups. Side effects were more commonly observed in the MN group (87%) than in MNT (24%, p < 0.0001) and MT groups (25%, p = 0.0003) at the first follow up.Conclusions and clinical relevanceTramadol plus metamizole combined or not with NSAID were well tolerated and clinically effective to treat moderate to severe pain in dogs with cancer and improved QL.     

Scanning tunneling microscopy and atomic force microscopy: application to biology and technology

The scanning tunneling microscope (STM) and the atomic force microscope (AFM) are scanning probe microscopes capable of resolving surface detail down to the atomic level. The potential of these microscopes for revealing subtle details of structure is illustrated by atomic resolution images including graphite, an organic conductor, an insulating layered compound, and individual adsorbed oxygen atoms on a semiconductor. Application of the STM for imaging biological materials directly has been hampered by the poor electron conductivity of most biological samples. The use of thin conductive metal coatings and replicas has made it possible to image some biological samples, as indicated by recently obtained images of a recA-DNA complex, a phospholipid bilayer, and an enzyme crystal. The potential of the AFM, which does not require a conductive sample, is shown with molecular resolution images of a nonconducting organic monolayer and an amino acid crystal that reveals individual methyl groups on the ends of the amino acids. Applications of these new microscopes to technology are demonstrated with images of an optical disk stamper, a diffraction grating, a thin-film magnetic recording head, and a diamond cutting tool. The STM has even been used to improve the quality of diffraction gratings and magnetic recording heads.     

Assessment of glutenin and phenotypic diversity of Syrian durum wheat landraces in relation to their geographical origin

Summary Glutenin and phenotypic diversity within Syrian landraces composed of Triticum turgidu var. durum and T. aestivum was compared and related to some geographical and climatological characteristics.Glutenin diversity was determined on the basis of the composition of the glutenin fraction in kernels using Gregorius' level of population differentiation (209-1) — being a modified Nei's measure of gene diversity (H)- and the Shannon-Weaver variation index (I). These two indices were highly correlated. A total of five Glu-A1 and nine Glu-B1 alleles that were not yet described were found. The phenotypic diversity was determined on the basis of the coefficients of variation of ten phenological and morphological traits.A highly significant positive correlation coefficient between the glutenin and phenotypic diversity indices was found. Both diversity indices were positively correlated with annual precipitation, minimum January temperature and altitude of the collection site. There was a negative correlation between genetic diversity and the maximum August temperature. Correlation of site characteristics was stronger with the glutenin diversity indices than with the phenotypic diversity index.Further could be concluded that all common glutenin alleles can be found in the landraces from the western coastal and mountainous part of Syria.     

Scanning tunneling microscopy of freeze-fracture replicas of biomembranes

The high resolution of the scanning tunneling microscope (STM) makes it a potentially important tool for the study of biomaterials. Biological materials can be imaged with the STM by a procedure in which fluid, nonconductive biomaterials are replaced by rigid and highly conductive freeze-fracture replicas. The three-dimensional contours of the ripple phase of dimyristoylphosphatidylcholine bilayers were imaged with unprecedented resolution with commercial STMs and standard freeze-fracture techniques. Details of the ripple amplitude, asymmetry, and configuration unobtainable by electron microscopy or x-ray diffraction can be observed relatively easily with the STM.     

Virtual Lesion Extension: A Measure to Quantify the Effects of Bacterial Blight on Rice Leaf CO(2) Exchange

ABSTRACT Virtual lesion extension was proposed as a measure to summarize the effects of foliar diseases with single spreading lesions on CO(2)-exchange parameters at the whole-leaf level. Visible lesion plus virtual lesion extension constitute a virtual lesion, in which CO(2) exchange was postulated to be nil. Virtual lesion extension can be derived for each photosynthesis parameter from gas-exchange measurements. Using a leaf-shape function, one-dimensional lesion length was translated into two-dimensional lesion area, and a relationship between visible and virtual severity can be established. The model was applied to measurements of leaf CO(2) exchange in rice leaves infected with Xanthomonas campestris pv. oryzae, the causal organism of rice bacterial blight. The model resulted in a virtual lesion extension of 1.1 cm for the gross CO(2)-exchange rate at light saturation, -3.9 cm for dark respiration rate, and 0 for initial light use efficiency. Reduced light interception due to a visible lesion caused reductions in net CO(2) assimilation, and small virtual lesion extensions only marginally reduced net CO(2) assimilation further. The additional reduction was smaller in case of longer leaves. Measurement of net photosynthesis rate along a transect from the base to the tip of infected leaves indicated that the location on the leaf blade where net photosynthesis decreased from normal to nil was centered around the lesion tip.     

Collaboration of farmers and breeders: Participatory crop improvement in perspective

Participatory Crop Improvement (PCI) has developed over the past decade as an alternative and complementary breeding approach to Formal Crop Improvement (FCI). In that context, PCI principally aims at more effectively addressing the needs of farmers in marginal areas in developing countries. This paper describes the rationale behind the emerging of the PCI-concept, the first experiences, and its place in a development-context. The relation with in situ conservation of plant genetic resources is briefly described. The paper uses the distinction in PCI between PVS (Participatory Varietal Selection, i.e. participatory selection among varieties and advanced materials) and PPB (Participatory Plant Breeding, i.e. selection within segregating materials). While successful experiences of PVS are reported, the potentials of PPB are still to be explored. Among other issues, this article pays attention to Genotype x Environment interaction: while G × E interaction is recognised as an important issue in plant breeding and a justification for PCI, the implications for the design of selection systems with farmer participation, and, eventually the potential of PPB has only been analysed to a limited extend. Questions in relation to materials, breeding strategies and selection procedures to achieve sufficient progress in the different crops and environments are identified; these will however remain unanswered until more experiences from the field are available. This revised version was published online in August 2006 with corrections to the Cover Date.