A proteomic analysis of organelles from Arabidopsis thaliana

We introduce the use of Arabidopsis thaliana callus culture as a system for proteomic analysis of plant organelles using liquid-grown callus. This callus is relatively homogeneous, reproducible and cytoplasmically rich, and provides organelles in sufficient quantities for proteomic studies. A database was generated of mitochondrial, endoplasmic reticulum (ER), Golgi/prevacuolar compartment and plasma membrane (PM) markers using two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (2-D SDS-PAGE) and peptide sequencing or mass spectrometric methods. The major callus membrane-associated proteins were characterised as being integral or peripheral by Triton X-114 phase partitioning. The database was used to define specific proteins at the Arabidopsis callus plasma membrane. This database of organelle proteins provides the basis for future characterisation of the expression and localisation of novel plant proteins.     

Correction to: Interlaboratory Reproducibility of Contour Method Data Analysis and Residual Stress Calculation

Experimental Mechanics - The original version of this article has been corrected to include authors middle initials in the author list. The details given in this correction are correct.     

TRIUMF resonant ionization laser ion source

The range of isotopes available at the TRIUMF Isotope Separator Accelerator (ISAC) facility has been greatly enhanced by adding a Resonance Ionization Laser Ion Source (RILIS). A large wavelength range is accessible with the fundamental, second and third harmonic generation of titanium-sapphire laser light. In addition a dedicated laser is available for non-resonant laser ionization. The first on-line beam ⁶²Ga was delivered in Dec. 2004. In general RILIS improves the intensity, purity and emittance of ion beams. ⁶²Ga and ²⁶Al and Be beams have been delivered so far on-line. This work was financed by TRIUMF which is federally funded via a contribution agreement through the National Research Council of Canada.     

Measuring Multiple Residual-Stress Components using the Contour Method and Multiple Cuts

The conventional contour method determines one component of residual stress over the cross section of a part. The part is cut into two, the contour (topographic shape) of the exposed surface is measured, and Bueckner’s superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple residual-stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The multiple-cut contour method results agree very well with independent measurements using neutron diffraction and with a computational, finite-element model of the indentation process.     

Residual stresses in continuous-tungsten-fibre-reinforced Kanthal-matrix composites

Residual stresses were measured in four Kanthal matrix-continuous-tungsten-fibre composites (with different tungsten fibre volume fractions V f = 10, 20, 30 and 70 vol.%) using neutron diffraction. Parallel to the fibres the stress in the Kanthal ranged from 40 MPa ( V f = 10 vol.%) to 1100 MPa ( V f = 70 vol.%) compared with m1877 MPa ( V f = 10 vol.%) to m400 MPa ( V f = 70 vol.%) for the tungsten. Perpendicular to the fibres the stress ranged from m52 MPa ( V f = 10 vol.%) to 620 MPa ( V f = 70 vol.%) in the Kanthal compared with m778 MPa ( V f = 10vol.%) to m195 MPa ( V f = 70 vol.%) in the tungsten. Assuming that the measured residual stresses were solely thermal in origin, predictions were made using concentric cylinder and finite-element models. In the absence of hardening data the assumed material behaviour was elastic-perfectly plastic and the predictions underestimated the measured stresses for all volume fractions. Nevertheless the model results were consistent with the experimental measurements. The transverse stress in the fibres is discussed in the context of the interface normal stress, which is significant to the global mechanical response.     

Flow-induced noise of a wall-mounted finite airfoil at low-to-moderate Reynolds number

This paper presents an experimental investigation of the flow-induced noise created by a wall-mounted finite airfoil at low-to-moderate Reynolds number and zero angle of attack. Far-field noise measurements have been taken at a single observer location and with two perpendicular microphone arrays in an anechoic wind tunnel at Reynolds numbers of _Rec=9.2×10⁴–1.6×10⁵${\mathit{Re}}_c=9.2\times {10}^4–1.6\times {10}^5$, based on chord, and for a variety of airfoil aspect ratios (length to chord ratio of L/C=0.2–2$L/C=0.2–2$, corresponding to length to thickness ratio of L/T=1.7–16.7$L/T=1.7–16.7$). Additionally, surface oil-film visualisation images and unsteady velocity measurements taken in the near trailing edge wake are related to far-field noise measurements to determine the flow mechanisms responsible for noise generation. The results show that the wall-mounted finite airfoil radiates noise similar to a two-dimensional airfoil when L/T>8.3$L/T>8.3$. Despite the incoming boundary layer height at the junction being 1.30≤δ/T≤1.46$1.30\le \delta /T\le 1.46$, junction and tip flow suppresses tonal noise production for airfoil?s up to L/T=8.3$L/T=8.3$ at _Rec=9.2×10⁴–1.2×10⁵${\mathit{Re}}_c=9.2\times {10}^4–1.2\times {10}^5$. Trailing edge noise is found to be the dominant airfoil noise generation mechanism at frequencies above 1 kHz with the position of the noise source along the trailing edge determined by the proportion of the airfoil span influenced by flow at the airfoil–wall junction.     

Selective uncoupling of individual mitochondria within a cell using a mitochondria-targeted photoactivated protonophore

Depolarization of an individual mitochondrion or small clusters of mitochondria within cells has been achieved using a photoactivatable probe. The probe is targeted to the matrix of the mitochondrion by an alkyltriphenylphosphonium lipophilic cation and releases the protonophore 2,4-dinitrophenol locally in predetermined regions in response to directed irradiation with UV light via a local photolysis system. This also provides a proof of principle for the general temporally and spatially controlled release of bioactive molecules, pharmacophores, or toxins to mitochondria with tissue, cell, or mitochondrion specificity.     

Preparation of J-aggregate liposome dispersions and their chromic transformation

We report the preparation of aqueous liposome dispersions of J-aggregates formed by the amphiphilic merocyanine dye (MD). A series of liposome-forming lipids were dispersed together with MD J-aggregates at different molar ratios of MD to lipid. The MD J-aggregate dispersions prepared with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at the MD to DMPC ratio of 0.16 exhibit good dispersibility; that is, they can be readily redispersed without any flocculation even after their precipitation. By use of different counterions for the MD molecules, two types of J-aggregate dispersions, one that exhibits an absorption band (J-band) at 635 nm (type I) and the other at 600 nm (type II), were obtained. As an example of the use of MD J-aggregates liposome dispersions, the thermochromic transformation of MD J-aggregates was demonstrated. When the dispersions are heated, J-aggregates of type I transformed into type II at a certain temperature (T(disp)). The parameters that control the speed of the transformation and the value of T(disp) were determined.     

26 Al beam production by a solid state laser ion source at TRIUMF

Many experiments carried out at radioactive beam facilities require the production of intense, isotopically clean and isobar free beams of a particular isotope. At TRIUMF the addition of a resonant ionization laser ion source (TRILIS) enables a multitude of new beams and therefore new experiments to be carried out. ²⁶Al was one of the first radioactive ion beams delivered to an experiment using TRILIS. This paper outlines the development of the ²⁶Al ion beam for nuclear astrophysics.      

About the structure of two isomeric pyrazoloquinolines

Several structures are possible for the pyrazoloquinolines, formed in the Skraup synthesis from 5- or 6-aminoindazole. By nmr spectroscopic examination in the presence of shift reagents it was possible to assign the correct structures for both products, i.e., the angular 1H-pyrazolo-[3,4-f]quinoline ( 4 ) and 3H-pyrazolo[4,3-f]quinoline ( 2 ).