Analysis of volatile fatty acids in biological specimens by capillary column gas chromatography

A method was developed to analyze and quantify volatile fatty acids (VFA) such as acetic, propionic, butyric, isobutyric, valeric and isovaleric acids in biological specimens. To obtain good sample transfer into the chromatographic system an organic solvent had to be used together with an aqueous milieu, thus improving wetting properties of the liquid sample plug introduced into the column. Sample preparation was carried out under alkaline conditions in order to exclude or minimize sample losses due to sample transfer during the extraction and work-up procedure. A cold on-column injection was applied to avoid irregular discrimination of the various acids due to sample splitting and an automatic injection technique was used to accommodate the large number of samples generated from biological origin. Connection of a pre-column of wide internal diameter (0.53 mm) to the analytical column (0.32 m) was optimized and adapted to the nature of the injection solvent mixture consisting of acetonitrile, water and hydrochloric acid. To obtain well-separated and correctly quantifiable gas chromatographic peaks, it was essential to perform the chromatography under acidic aqueous conditions. Standard resolution conditions and response factors were evaluated. The chromatographic results of applying this method to biological specimens from both rats and humans are provided.     

Seam-Tracking for Friction Stir Welded Lap Joints

This article presents a method for automatic seam-tracking in friction stir welding (FSW) of lap joints. In this method, tracking is accomplished by weaving the FSW tool back-and-forth perpendicular to the direction of travel during welding and monitoring force and torque signals. Research demonstrates the ability of this method to automatically track weld seam positions. Additionally, tensile and S-bend test result comparisons demonstrate that weaving most likely does not reduce weld quality. Finally, benefits of this weave-based method to FSW of lap joints are discussed and methods for incorporating it into existing friction stir welding control algorithms (such as axial load control) are examined.     

Apoptotic Cells induce Proliferation of Peritoneal Macrophages

The interaction of macrophages with apoptotic cells is required for efficient resolution of inflammation. While apoptotic cell removal prevents inflammation due to secondary necrosis, it also alters the macrophage phenotype to hinder further inflammatory reactions. The interaction between apoptotic cells and macrophages is often studied by chemical or biological induction of apoptosis, which may introduce artifacts by affecting the macrophages as well and/or triggering unrelated signaling pathways. Here, we set up a pure cell death system in which NIH 3T3 cells expressing dimerizable Caspase-8 were co-cultured with peritoneal macrophages in a transwell system. Phenotype changes in macrophages induced by apoptotic cells were evaluated by RNA sequencing, which revealed an unexpectedly dominant impact on macrophage proliferation. This was confirmed in functional assays with primary peritoneal macrophages and IC-21 macrophages. Moreover, inhibition of apoptosis during Zymosan-induced peritonitis in mice decreased mRNA levels of cell cycle mediators in peritoneal macrophages. Proliferation of macrophages in response to apoptotic cells may be important to increase macrophage numbers in order to allow efficient clearance and resolution of inflammation.     

NIST structures division: They don’t build the buildings — they make the buildings better

hen the hurricane winds blow, when the earthquakes rumble, when the floodwaters sweep through, when fire rages, why do some buildings come down while others stay up? Learning the answer — and then making improvements to the next generation building code — is the job of the Structures Division at the National Institute of Standards and Technology (NIST). These scientists and engineers investigate structural failures caused by natural forces, as well as those resulting from errors in design and construction or material flaws. And August is one of the months of the year in which the assessment teams spend the most time out on the field due to such natural disasters as the massive flood in Alaska in 1967, Hurricane Camille in 1969, Hurricane Andrew in 1992, and the 7.4 magnitude earthquake in Turkey in 1999.     

Synthetic impedance for implementation of piezoelectricshunt-damping circuits

Piezoelectric transducer (PZT) patches may be attached to structures to reduce vibration. The PZT patches essentially convert vibrational mechanical energy to electrical energy. The electrical energy can be dissipated via an electrical impedance. The authors introduce a method of implementing any arbitrary impedance, using a digital signal processor. The “synthetic impedance” is demonstrated on a resonant simply supported beam     

Highly resonant controller for multimode piezoelectric shuntdamping

A new controller structure for piezoelectric shunt damping is proposed. The controller has a highly resonant structure and is implemented digitally on a piezoelectric laminate structure. Experimental results are presented demonstrating the effectiveness of the controller in suppressing structural vibrations     

A three-dimensional optical photonic crystal

We report on the successful fabrication of a working three-dimensional (3D) crystal operating at optical wavelength λ. The minimum feature size of the 3D structure is 180 nm. The 3D crystal is free from defects over the entire 6-inch silicon wafer and has an absolute photonic bandgap (PBG) centered at λ~1.6 μm. Our data provides the first conclusive evidence for the existence of a complete 3D PBG in optical λ. This development will pave the way to tinier, cheaper, more effective waveguides, optical switches and lasers     

The finite element modelling of laser soldering for electronic assemblies

The laser provides a controllable means of supplying localized energy for solder joint formation and is a valuable tool in electronics manufacture. The modelling of heating behaviour in typical structures requires consideration of many different phenomena and the resulting models can become complex. The work described here shows that, given appropriate modelling assumptions, finite element models are able to give accurate predictions of heating in high-pin count devices as well as a valuable insight into the important factors affecting the success of laser soldering operations. In particular, it is shown here that conduction through the body of the component being soldered does not significantly affect heating of the solder but that variations in copper track thickness can result in a doubling of the required soldering time. In addition, it is shown that conduction through the printed circuit board is important when using a scanned laser beam to solder multiple joints. Copyright © 2002 John Wiley & Sons, Ltd.     

UV-B radiometry and dosimetry for solar measurements

Glycosaminoglycan administration has favourable effects on morphological and functional renal abnormalities in different models. The possibility that exogenous glycosaminoglycans modulate glomerular matrix synthesis was explored in both primary and SV40-MES13 murine mesangial cell cultures. On both cell types, both low-molecular-weight heparin and different glycosaminoglycans showed dose-dependent inhibition of proliferation and increase of 35SO4(2)-uptake. After 36 h the cell compartment contained a spectrum of 35S-molecules of less than 200 kDa; under heparin treatment, the two main 35SO4(2)-components (high and medium MW) increased by 16 and 37% respectively. Susceptibility to glycosidases revealed that heparin promotes the expression of heparan sulphate and increases that of chondroitin sulphate. Moreover, heparin modifies the expression of decorin and biglycan, involved in adhesion and fibrillogenesis, while not affecting perlecan. The extracellular matrix modulation in renal cells, for which the sulphation type and ratio of heparin are crucial, may thus explain the beneficial renal effects of heparin.     

Distribution and translocation of isoforms of protein kinase C in rat submandibular acinar cells

The distribution of six isoforms of protein kinase C (PKC) in seromucous acinar cells of rat submandibular gland was examined and their translocation from the cytosolic- to the membrane fraction after different stimuli investigated. Western blotting, immunostaining with isoform-specific antibodies and scanning densitometry showed that PKC-alpha and epsilon were distributed fairly evenly between the cytosol and membranes in resting cells, while isoforms- beta, delta and zeta were all predominantly localized (over 80%) in membranes. PKC-gamma was not detected. PKC-alpha was mobilized to the membrane fraction by the phorbol ester, TPA, but not by the phosphoinositide-coupled agonists carbachol, methoxamine and substance P (SP). PKC-epsilon was translocated by TPA and carbachol but not by SP or methoxamine. Biochemical assay of total PKC confirmed that cytosolic enzyme activity was significantly reduced by TPA and carbachol to 29% and 75% respectively of control levels. These results suggest that muscarinic regulation of the mucosecretory response in the rat submandibular gland may be mediated by the PKC-epsilon isoform.