On the effective lagrangian in the supersymmetric N = 1 Yang-Mills theory

It is shown that supersymmetry breaking does not occur in a supersymmetric Yang-Mills theory with an effective lagrangian (EL) constructed of the simplest composite colourless superfields. Our arguments appear also to be valid for the case of still more complicated models of EL.     

Pyridinethiones. IX preparation of ricinidine,thioricinidine and other 2(1H)-pyridones and -thiones related to nicotinic acid

2(1H)-Pyridones and -thiones related to 1-substituted nicotinic acid derivatives have been prepared via the corresponding l-substituted-3-formyl-2(1H)-pyridones and -thiones. A number of synthetic procedures for the interconversion of functional groups in these nicotinic acid derivatives are given i.e. preparation of the aldoximes, nitriles, carboxamides and carboxylic acids as well as the 3- hydroxyalkyl derivatives. The course of the basic peroxide oxidation of the l-substituted-3-formyl-2(1H)-pyridinethiones is found to be very dependent upon the electronegativity of the 1-substituent. A preparation of ricinidine is also described.     

Retention index values of hydrocarbons on open-tubular columns coated with methylsilicone liquid phases

Summary The influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on the retention index values of hydrocarbons on methylsilicone liquid phases is discussed. Data obtained on methylsilicones and squalane are compared. Retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are listed.     

Precision analyses of manganese in rocks by neutron activation analysis

A simple and rapid procedure for the determination of manganese in rocks by neutron activation and γ-spectrometry is presented. The precision of the method calculated from analyses of standard rocks is of the order 1.5–2%, and an accuracy of ±2% is attainable. The method is applicable to most types of geological samples, and should be superior to conventional methods used in rock analysis.     

Particle electrophoresis as a tool to understand the aggregation behavior of red blood cells

Red blood cell (RBC) electrophoresis measurements in polymer solutions have recently been introduced as a promising approach for investigating polymer-cell interactions near the RBC surface. A polymer-poor depletion layer near the RBC has been demonstrated: for depletion layers thicker than the double layer, viscosity within the depletion layer, rather than suspending medium viscosity, affects cell mobility. Using a well-documented model of sepsis in rats, we have induced RBC membrane damage, and then measured the electrophoretic mobility of rat RBC from control and septic animals. Mobility measurements were carried out for cells suspended in polymer-free buffer and in 0.5-2% solutions of dextran 500 (500 kDa molecular mass); RBC aggregation in autologous plasma and in dextran 500 was also studied. Our results indicate: (i) as anticipated from prior studies, the aggregation of RBC from septic animals is markedly enhanced (p<0.001) in plasma and in 0.5-1% dextran; (ii) the mobility of septic RBC in polymer-free buffer was identical to control, whereas cells from septic animals had lower mobilities in 0.5% dextran; (iii) Over the range studied (0.5-2%), the mobility of RBC from septic animals was less sensitive to increases of dextran concentration and hence medium viscosity. These mobility-aggregation findings can be partially interpreted in terms of a depletion model for RBC aggregation; alterations of RBC surface charge and the hydrodynamic friction within the cell's glycocalyx may also be involved. In overview, we believe that these results suggest the merits of microelectrophoresis for exploring protein or polymer behavior near biological particles and the potential value of future studies for understanding cell-cell interactions.     

Influence of solvent quality on the growth of polyelectrolyte multilayers

The effect of solvent conditions on the growth of polyelectrolyte (PE) multilayer films comprising poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate sodium salt) (PSS) on planar substrates was investigated by means of surface plasmon resonance spectroscopy (SPRS), quartz crystal microbalance (QCM), and atomic force microscopy techniques. The solvent quality was varied by the addition of ethanol to the PE solutions used for deposition of the layers, thus tuning the relative strength of electrostatic and secondary intermolecular and intramolecular interactions. Experiments were performed with PE solutions both without added electrolyte and containing 0.5 M NaCl. Decreasing the solvent quality (i.e., increasing the amount of ethanol in the adsorption solution) resulted in a marked increase of both the multilayer film thickness and mass loading, as determined from the SPRS spectra and QCM frequency shifts, respectively. With the solution composition approaching the precipitation point, thick PAH/PSS films were formed due to the screening of the electrostatic intra- and interchain repulsions and enhanced hydrophobic interactions between the polyelectrolyte chains. However, the films formed from water/ethanol mixtures remained stable upon subsequent exposure to water or salt-containing solutions: no significant film desorption occurred after up to 24 h of exposure to water or 0.5 M NaCl solutions. In addition, the effect of postdeposition exposure to water/ethanol mixtures was investigated for PE multilayers assembled from aqueous solutions. In this case, the optical thickness of the films was determined during exposure to water/ethanol mixtures, and instead of swelling, the polyelectrolyte films collapse to the surface as a result of the unfavorable segment-solvent interactions.     

Self-assembly, DNA complexation, and pH response of amphiphilic dendrimers for gene transfection

Cationic lipids and polymers are routinely used for cell transfection, and a variety of structure-activity relation data have been collected. Few studies, however, focus on the structural aspects of self-assembly as a crucial control parameter for gene delivery. We present here the observations collected for a set of cationic dendritic amphiphiles based on a stiff tolane core (1-4) that are built from identical subunits but differ in the number and balance of their hydrophobic and cationic hydrophilic moieties. We established elsewhere that vectors 3 and 4 have promising transfection properties. Scanning probe microscopy (AFM, STM), cryo-transmission electron microscopy (cryo-TEM), and Langmuir techniques provide insight into the self-assembly properties of the molecules under physiological conditions. Furthermore, we present DNA and pH "jump" experiments where we study the response of Langmuir films to a sudden increase in DNA concentration or a drop in pH. We find that the primary self-assembly of the amphiphile is of paramount importance and influences DNA binding, serum sensitivity, and pH response of the vector system.     

Curvature driven transport of mouse macrophages in a pulsating magnetic garnet film ratchet

Magnetic fields varying on the colloidal length scale are used for the directed transport of magnetically labeled biological cells. The transport is achieved by using the ratchet effect which relies on an asymmetric, symmetry broken periodic potential where nonequilibrium fluctuations or oscillations generate a net cell current. Ferrofluid ingested mouse macrophages were placed on a magnetic garnet film with alternating stripe domain patterns, and a pulsating magnetic potential is provided by superposing an oscillating magnetic field normal to the film. The symmetry of the resulting periodic stripe potential is broken locally by the curvature of the stripes. We show, both experimentally and theoretically, the curvature of such stripes required for inducing directed transport of the macrophages in the ratchet. This may be useful for microfluidic devices such as a digital colloidal shift register for magnetically labeled biological cells.     

Localized and delocalized motion of colloidal particles on a magnetic bubble lattice

We study the motion of paramagnetic colloidal particles placed above magnetic bubble domains of a uniaxial garnet film and driven through the lattice by external magnetic field modulation. An external tunable precessing field propels the particles either in localized orbits around the bubbles or in superdiffusive or ballistic motion through the bubble array. This motion results from the interplay between the driving rotating signal, the viscous drag force and the periodic magnetic energy landscape. We explain the transition in terms of the incommensurability between the transit frequency of the particle through a unit cell and the modulation frequency. Ballistic motion dynamically breaks the symmetry of the array and the phase locked particles follow one of the six crystal directions.     

Palladium-catalyzed monoamination of dihalogenated benzenes

The palladium-catalyzed monoamination of symmetric dibromobenzenes can be performed using a catalyst based on Pd₂dba₃ and BINAP in the presence of NaO(t-Bu). The analogous transformation of non-symmetric bromoiodobenzenes is most effectively performed with Xantphos as the ligand, while reactions with BINAP were non-selective. These transformations can be scaled uneventfully to >10 g quantities. They do not require drybox or Schlenk techniques, and all reagents are weighed out in air. The resulting monobromoanilines are versatile intermediates for further synthetic transformations.