Template synthesis and forming electrical contacts to single Au nanowires by focused ion beam techniques.

Metallic Au nanowires were electrochemically synthesized in 20 µm thick ion track etched polycarbonate membranes with the nominal pore diameter of 200 nm. Scanning and transmission electron microscopy analysis and x-ray diffraction of samples revealed that the nanowires are dense with a fcc [Formula: see text] texturing. The I-V characteristics of a single Au nanowire were investigated using a four-point microprobe set-up. The Au nanowire was placed in electrical contact with electrodes patterned on planar substrates using a dual-beam focused ion beam technique. The resistivity of the Au nanowires was found to be 2.8 × 10(-4) Ω cm.

Cell cycle regulation in the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius.

The regulation and co-ordination of the cell cycle of the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius was investigated with antibiotics. We provide evidence for a core regulation involving alternating rounds of chromosome replication and genome segregation. In contrast, multiple rounds of replication of the chromosome could occur in the absence of an intervening cell division event. Inhibition of the elongation stage of chromosome replication resulted in cell division arrest, indicating that pathways similar to checkpoint mechanisms in eukaryotes, and the SOS system of bacteria, also exist in archaea. Several antibiotics induced cell cycle arrest in the G2 stage. Analysis of the run-out kinetics of chromosome replication during the treatments allowed estimation of the minimal rate of replication fork movement in vivo to 250 bp s-1. An efficient method for the production of synchronized Sulfolobus populations by transient daunomycin treatment is presented, providing opportunities for studies of cell cycle-specific events. Possible targets for the antibiotics are discussed, including topoisomerases and protein glycosylation.

Transfer of continuous-relief diffractive structures into diamond by use of inductively coupled plasma dry etching.

The transfer of continuous-relief diffractive structures from resist into diamond by use of direct-write electron-beam lithography followed by dry etching in an inductively coupled plasma is demonstrated. The gases used for the diamond etching are O(2) and Ar. The chemical-vapor-deposited diamond substrate is of optical quality. Our results show that the transfer process generates fairly smooth etched structures. Blazed gratings with periods of 45mum and Fresnel lenses have been manufactured. The blazed gratings have been optically evaluated with a femtosecond laser operating at 400 nm. The diffraction efficiency was 68% in the first order, with a theoretical value of 100%. We intend to investigate the transfer process further and then to fabricate diffractive and refractive elements for use with Nd:YAG high-power lasers.

X-cut miniature tuning forks realized by ion track lithography.

With the recently developed ion track lithography based on the selective etching, widening, and merging of ion-induced defects collectively resembling a superimposed anisotropy in certain areas as defined by a stencil mask, 39-kHz x-cut miniature tuning forks with a tine size of 331x2, 500x42 mum and a Q-value of up to 42 000 were fabricated from single crystalline quartz mostly to demonstrate this new technique's ability to structure difficult cuts, but also to benefit from the much simpler electrode configuration possible with this cut in comparison with ordinary z-cut watch tuning forks.

Changes in cell size and DNA content in Sulfolobus cultures during dilution and temperature shift experiments.

Stationary-phase cultures of different hyperthermophilic species of the archaeal genus Sulfolobus were diluted into fresh growth medium and analyzed by flow cytometry and phase-fluorescence microscopy. After dilution, cellular growth started rapidly but no nucleoid partition, cell division, or chromosome replication took place until the cells had been increasing in size for several hours. Initiation of chromosome replication required that the cells first go through partition and cell division, revealing a strong interdependence between these key cell cycle events. The time points at which nucleoid partition, division, and replication occurred after the dilution were used to estimate the relative lengths of the cell cycle periods. When exponentially growing cultures were diluted into fresh growth medium, there was an unexpected transient inhibition of growth and cell division, showing that the cultures did not maintain balanced growth. Furthermore, when cultures growing at 79 degrees C were shifted to room temperature or to ice-water baths, the cells were found to "freeze" in mid-growth. After a shift back to 79 degrees C, growth, replication, and division rapidly resumed and the mode and kinetics of the resumption differed depending upon the nature and length of the shifts. Dilution of stationary-phase cultures provides a simple protocol for the generation of partially synchronized populations that may be used to study cell cycle-specific events.

Vegetable oils instead of xylene in tissue processing.

In an effort to improve working conditions in the histopathologic laboratory, we have investigated whether less toxic substances may be substituted for the toxic organic solvent xylene currently in use. Xylene is used in the clearing as well as the deparaffinization process. We have tested whether the substitution of xylene by olive oil and coconut oil leads to any difference in the quality of the histologic sections. Two tissue blocks from each of 232 specimens sent for histopathologic evaluation were subjected to parallel processing in xylene and oil. The specimens represented a broad spectrum of tissue types. All sections were stained with hematoxylin-eosin to permit evaluation of histologic and cytologic details. Furthermore, a range of histochemical and immunohistochemical stainings were applied to a subgroup of tissue sections. The results showed qualitative differences between xylene-processed and oil-processed tissue in only a minority of cases. In no cases were the oil-processed samples considered less suitable for histologic diagnosis. In the histochemical and immunohistochemical stainings, no differences were registered. Although the long-term stability of oil-processed tissue remains to be clarified, we conclude that less toxic vegetable oil may probably be substituted for xylene without losing valuable diagnostic information.