Integrated microanalytical technology enabling rapid and automated protein identification

Protein identification through peptide mass mapping by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a standard technique, used in many laboratories around the world. The traditional methodology often includes long incubations (6-24 h) and extensive manual steps. In an effort to address this, an integrated microanalytical platform has been developed for automated identification of proteins. The silicon micromachined analytical tools, i.e., the microchip immobilized enzyme reactor (mu-chip IMER), the piezoelectric microdispenser, and the high-density nanovial target plates, are the cornerstones in the system. The mu-chip IMER provides on-line enzymatic digestion of protein samples (1 microL) within 1-3 min, and the microdispenser enables subsequent on-line picoliter sample preparation in a high-density format. Interfaced to automated MALDI-TOF MS, these tools compose a highly efficient platform that can analyze 100 protein samples in 3.5 h. Kinetic studies on the microreactors are reported as well as the operation of this microanalytical platform for protein identification, wherein lysozyme, myoglobin, ribonuclease A, and cytochrome c have been identified with a high sequence coverage (50-100%).     

Inelasticity in isothermal martensite transformation

Conclusions  

Real-Time Imaging through Optical Fiber Array-Assisted Laser-Induced Fluorescence of Capillary Electrophoretic Enantiomer Separations

An advanced detection system based on laser-induced fluorescence imaging for capillary electrophoresis (CE) is presented. An optical fiber array was constructed for collection and transportation of the emitted fluorescent light to the charge-coupled device (CCD) camera. The fiber array makes the setup compact compared with a setup where the capillary is imaged through a camera objective. The imaging detector captures the sample zones in motion during the migration through the capillary. This allows unique studies on dynamic events otherwise unrevealed. During the study, unexplained nonlinear migration behavior was revealed. Enantiomer separations of dansylated amino acids using cyclodextrins, imaged between 1.5 and 12 cm of a 28-cm-long 50-μm i.d. capillary, were used for evaluation of the system. Comparing the optical fiber array with a camera lens system, the signal-to-noise-ratio (S/N) was 10 times higher. This is due to a combination of both higher signal and lower noise levels. To improve the S/N ratio further, a computer program for signal processing was designed. Using dichlorofluorescein, a concentration limit of detection (CLOD) of 350 pM was achieved and improved 10 times to 35 pM with computer postprocessing using 79 images. This is equal to 400 zeptomole for a 3-mm-long sample zone in a 50-μm i.d. capillary.     

A design for low-flow sheathless electrospray emitters

An extremely simple design has been developed for producing durable sheathless electrospray emitters that give highly stable electrospray for unlimited lifetimes. The emitters can be fashioned from any style fused-silica capillary and are ideally suited for generating "all-in-one" microcolumn-emitter systems thus eliminating unwanted void volumes. The emitters give stable electrospray at low (30 nL/min) as well as high (1 mL/min) flow rates without the aid of nebulizing gas. Fabrication of these emitters (aka the "fairy dust" technique) does not involve the use of a metallized coating but rather the adherance of 2-μm gold particles to the capillary tip resulting in a robust approach to the problem of making an electrical contact with the electrospray solvent.     

Simple and compact, all-fibre retro-reflector for cladding-pumped fibre lasers

Proposed is an all-fibre retro-reflector realised via shaping a fibre end into a right-angled cone for a pump reflector in cladding-pumped fibre lasers. The conical-shaped fibre-optic retro-reflector allows folded, total internal reflections for pump beams that propagate in the inner cladding of a double-clad fibre. The proposed scheme was applied to a cladding-pumped ytterbium-doped fibre laser and readily achieved over 55% of reflection for the unabsorbed pump throughput, thereby generating 29% more signal output power than without the pump retro-reflector     

Role of cyclooxygenase-2 for fluid secretion by the inflamed gallbladder mucosa

Heterotrimeric GTP-binding protein (G-protein)-coupled receptors are able to induce a variety of responses including cell proliferation, differentiation, and activation of several intracellular kinase cascades. Prominent among these kinases are the activation of mitogen-activated protein (MAP) kinase, including the extracellular signal-regulated kinases (ERKs), ERK1 and ERK2 (p44mapk and p42mapk, respectively); stress-activated protein kinases (SAPKs/JNKs); and p38 kinase. These receptors signal through G-proteins. Recent data have shown that the activation of mitogen-activated protein/ERK kinase induced by G-protein-coupled receptors is mediated by both Galpha and Gbetagamma subunits involving a common signaling pathway with receptor-tyrosine-kinases. Gbetagamma-mediated mitogen-activated protein kinase activation is mediated by activation of phosphoinositide 3-kinase, followed by a tyrosine phosphorylation event, and proceeds in a sequence of events that involve functional association among the adaptor proteins Shc, Grb2, and Sos. SAPKs/JNKs and p38 are able to be activated by Gbetagamma proteins in a pathway involving Rho family proteins including RhoA, Rac1, and Cdc42.     

Application of high Tc superconductors asfrequency selective surfaces: experiment and theory

The use of YBa₂Cu₃O_7-x and Tl₂CaBa₂Cu₂O₈ high-temperature superconducting thin films to fabricate frequency selective surfaces (FSS) at millimeter-wave frequencies (75-110 GHz) is discussed. An analytical/numerical model was applied, using a Floquet expansion and the method of moments, to analyze bandstop superconducting frequency selective surfaces. Experimental results were compared with the model, and showed agreement with resonant frequency prediction with an accuracy of better than 1%. The use of the superconducting frequency selective surfaces as quasi-optical millimeter-wave bandpass filters was also demonstrated