The effect of gravity modulation on solutal convection during directional solidification

During directional solidification of a binary alloy at constant velocity, thermosolutal convection may occur due to the temperature and solute gradients associated with the solidification process. For vertical growth in an ideal furnace (lacking horizontal gradients) a quiescent state is possible. For a range of processing conditions, the thermal Rayleigh number is sufficiently small that the stabilizing role of the thermal field during growth vertically upwards may be neglected, and only solutal convection need be considered. The effect of a time-periodic vertical gravitational acceleration (or equivalently vibration) on the onset of solutal convection is calculated based on linear stability using Floquet theory. We find that a stable base state can be destabilized due to modulation, while an unstable state can be stabilized. The flow and solute disturbance fields show both synchronous and subharmonic temporal response to the driving sinusoidal modulation.     

Synthesis and Electrochemistry of Alkylidynetrihydridotriruthenium Clusters with Apical π-Substituents

The clusters, (-H)₃Ru₃( ₃-CY)(CO)_9–n (PPh₃) _n [Y=–CH₂CHCH₂, n=0 (1); Y=–CH₂CHCH₂, n=3 (2); Y=–C₆H₄CH₃, n=0 (3); Y=–C₆H₄CH₃, n=3 (4)], have been synthesized in good yields and characterized by IR and NMR spectroscopy and by elemental analysis. The electrochemical properties of these clusters is also reported. These data indicate that the -system of the apical substituent does not interact significantly with the cluster and should be available for further chemistry.     

Detection of several electronically metastable atomic states by gas phase EPR

Several atomic metastable species including N(²D_{$\text{5}\text{2}$}), N(²D_{$\text{3}\text{2}$}), N(²P_{$\text{3}\text{2}$}), O(¹D₂), Ne(³P₂), Ar(³P₂), Kr(³P₂ and Xe(³P₂) have been detected by gas phase electron paramagnetic resonance (EPR) in a discharge-flow system. Spectra and absolute concentration are presented.     

Application of combined liquid chromatography/mass spectrometry (LC/MS): analysis of petroporphyrins and meibomian gland waxes.

Application of the moving belt LC/MS interface is illustrated by two diverse examples, one from the field of petroporphyrin chemistry, the other, a sample of high molecular weight waxes from the steer meibomian gland (eye). Petroporphyrins are difficult of convert to derivatives suitable for GC analysis and the advantages of analysis by a combined separation/identification method are well demonstrated by the LC/MS runs. High molecular weight waxes can be saponified and derivatized for other analyses such as GC and GC/MS, but information regarding the distribution of alcohol and acid in the combined state is destroyed. This study shows that such information can be obtained by a combined LC/MS analysis without chemical manipulation of the sample.     

The vibration produced by multiple point defects in a rolling element bearing

A model for the high-frequency vibration produced by a single point defect on the inner race of a rolling element bearing under radial load is extended to describe the vibration produced by multiple points defects. The model incorporates the effects of bearing geometry, speed, load distribution, transfer function and the decay of vibration. A comparison of predicted and measured spectra for a bearing with two point defects confirms satisfactory performance of the model.     

A facile and modular synthesis of phosphinooxazoline ligands

The copper(I) iodide catalyzed phosphine/aryl halide coupling procedure of Buchwald et al. provides modular, robust, and scaleable access to phosphinooxazoline (PHOX) ligands. The advantages of this method are highlighted by the convenient synthesis of PHOX ligands with varied steric and electronic properties, which would be challenging to synthesize by other protocols.     

Desmoplakin is important for proper cardiac cell-cell interactions

Normal cardiac function is maintained through dynamic interactions of cardiac cells with each other and with the extracellular matrix. These interactions are important for remodeling during cardiac growth and pathophysiological conditions. However, the precise mechanisms of these interactions remain unclear. In this study we examined the importance of desmoplakin (DSP) in cardiac cell-cell interactions. Cell-cell communication in the heart requires the formation and preservation of cell contacts by cell adhesion junctions called desmosome-like structures. A major protein component of this complex is DSP, which plays a role in linking the cytoskeletal network to the plasma membrane. Our laboratory previously generated a polyclonal antibody (1611) against the detergent soluble fraction of cardiac fibroblast plasma membrane. In attempting to define which proteins 1611 recognizes, we performed two-dimensional electrophoresis and identified DSP as one of the major proteins recognized by 1611. Immunoprecipitation studies demonstrated that 1611 was able to directly pulldown DSP. We also demonstrate that 1611 and anti-DSP antibodies co-localize in whole heart sections. Finally, using a three-dimensional in vitro cell-cell interaction assay, we demonstrate that 1611 can inhibit cell-cell interactions. These data indicate that DSP is an important protein for cell-cell interactions and affects a variety of cellular functions, including cytokine secretion.     

Modeling the binding of peptides on carbon nanotubes and their use as protein and DNA carriers

An in-depth study of a novel functionalization of carbon nanotubes for their application as protein and DNA carriers is presented. First, the optimum conditions for the dispersion of single-walled carbon nanotubes (SWCNTs) with amphiphilic polypeptides were obtained, and the SWCNT–polypeptide complexes were characterized by different techniques (UV–Vis-NIR, CD, and AFM). Based on the properties of the SWCNT–polypeptide complexes, a model that characterizes the adsorption of natural proteins onto SWCNT was described for the first time. This model predicts the adsorption of natural proteins on SWCNTs based on the protein structure and composition, and therefore, allows the design of methods for the preparation of SWCNT–protein complexes. Besides, the use of cationic-designed amphiphilic polypeptides to disperse SWCNTs is applied for subsequent and efficient binding of DNA to carbon nanotubes by a bilayer approach. Therefore, in this article, we develop procedures for the use of SWCNTs as protein and DNA carriers. The systems were delivered into cells showing that the efficiency of delivery is affected by the charge of the complexes, which has important implications in the use of SWCNT as platforms for protein and DNA binding and subsequent use as delivery systems.