This Note describes the suitability of a number of techniques of potential use in studying cracking in lead-free solder joints, and hence their use in assessing joint lifetimes. Cracks induced into solder joints of chip resistors on FR4 substrates, were studied using micro-sectioning, dye penetration, mechanical test and thermal conductivity techniques. The work previously reported [1] has been...

Some binary lipid mixtures form coexisting liquid phases when spread at the airrwater interface. This work describes the pressure–composition phase diagrams of binary mixtures of four unsaturated phosphatidylcholines with dihydrocholesterol. These four binary mixtures have critical compositions of approximately fifty mole percent, and average critical exponents of 0.25 "0.07. The data can also ...

Tag der mündlichen Prüfung am: The voyage of discovery is not in seeking new landscapes but in having new eyes-Marcel Proust ABBREVIATIONS 6 Abbreviations ADAM 1-aminoadamantam ADP Adenosine diphosphate ATP Adenosine triphosphate AHT Anhydrotetracycline Amp r Resistance towards ampicilin aphA3, Kan r Resistance towards kanamycin APS Ammoniumperoxodisulfate bp Base pairs BCA Bicinchoninic acid c...

DNA oligonucleotides with appropriate sequences can form a stable duplex in which the two strands are paired in a parallel orientation instead of as the conventional antiparallel double helix of B-DNA. In parallel-stranded DNA (ps-DNA) base pairing is noncanonical with the glycosidic bonds In a trans orientation. The two grooves are equivalent. We have synthesized DNA duplexes consisting of a c...

An abundant yeast mitochondrial 40 kDa protein (p40) binds with high specificity to the 5'-untranslated region of cytochrome c oxidase subunit II (COX2) mRNA. Using mobility shift and competition assays, we show here that purified p40 complexes with the leaders of all eight mitochondrial mRNAs of Saccharomyces cerevisiae. The location of the protein binding site on the different leaders is not ...

GABA type A (GABA(A)) receptors are functionally regulated by external protons in a manner dependent on the receptor subunit composition. Although H(+) can regulate the open probability of single GABA ion channels, exactly what residues and receptor subunits are responsible for proton-induced modulation remain unknown. This study resolves this issue by using recombinant alpha1betai subunit GABA...

Values of the bending modulus KC and the tilt modulus Kθ are reported for single component lipid bilayers. The lipids studied have the common names DOPC, DMPC, diC22:1PC, SOPC, POPC, diPhyPC, DLPC, DPPC, DHPC and DEPC, listed in the order of number of samples examined. The experimental method, thus far the only one that measures the tilt modulus of lipid bilayers, first obtains diffuse X-ray sc...

The chemical probes potassium permanganate (KMnO4) and diethylpyrocarbonate (DEPC) can be used to study the conformational flexibility of short tracts of adenine (A-tracts) present in DNA. With these probes, we demonstrate that a novel distortion is induced in a 5 base pair A-tract at low temperature. Formation of this distorted A-tract structure, which occurs in a DNA fragment from the promote...

Efficient mechanisms of H(+) ion extrusion are crucial for normal NADPH oxidase function. However, whether the NADPH oxidase-in analogy with mitochondrial cytochromes-has an inherent H(+) channel activity remains uncertain: electrophysiological studies did not find altered H(+) currents in cells from patients with chronic granulomatous disease (CGD), challenging earlier reports in intact cells....

Diffusion and permeation in polymeric materials is of fundamental importance in many applications and is the subject of considerable scientific interest. Measurement methods for determining permeation through polymer sheets and within polymeric materials have been reviewed. An overview of the generic mechanisms involved reveals dependence of these properties on a wide range of factors, some rel...