Electron and recoil ion momentum imaging with a magneto-optically trapped target.

A reaction microscope (ReMi) has been combined with a magneto-optical trap (MOT) for the kinematically complete investigation of atomic break-up processes. With the novel MOTReMi apparatus, the momentum vectors of the fragments of laser-cooled and state-prepared lithium atoms are measured in coincidence and over the full solid angle. The first successful implementation of a MOTReMi could be realized due to an optimized design of the present setup, a nonstandard operation of the MOT, and by employing a switching cycle with alternating measuring and trapping periods. The very low target temperature in the MOT (∼2 mK) allows for an excellent momentum resolution. Optical preparation of the target atoms in the excited Li 2(2)P3/2 state was demonstrated providing an atomic polarization of close to 100%. While first experimental results were reported earlier, in this work, we focus on the technical description of the setup and its performance in commissioning experiments involving target ionization in 266 nm laser pulses and in collisions with projectile ions.

Excision of pre-ulcerative forms of Buruli ulcer disease: a curative treatment?

BACKGROUND: Previous investigations have revealed that Mycobacterium ulcerans is extensively distributed spatially throughout ulcerative lesions, including in the margins of excised tissue. In contrast, bacilli in pre-ulcerative lesions are assumed to be concentrated in the center of the lesion. In order to assess the extent to which the surgical excision of pre-ulcerative lesions is capable of removing all infected tissue, we subjected the excision margins of pre-ulcerative lesions to laboratory analysis. PATIENTS AND METHODS: Eleven patients with laboratory-confirmed pre-ulcerative lesions were included in the study. The diameter of the lesion and excised tissue and the "surgical distance" between the border of the lesion and excision margin were measured. The entire excision margin was cut into segments and subjected to IS2404 PCR. RESULTS: The results from the PCR analysis on the samples of excision margins were highly significantly associated with the surgical distance (p < 0.001). The margin samples of nodules were significantly more often PCR positive than the plaques (p = 0.025). The size of the lesion and the size of the excised tissue did not significantly influence the PCR results. Statistically, a surgical distance of more than 9 mm was found to reduce the risk of remaining infected tissue to less than 10%, that of 13 mm to reduce the risk to less than 5%, and that of 25 mm to reduce the risk to nearly 0%. CONCLUSION: The results of this study show that in preulcerative Buruli ulcer disease, bacilli may extend beyond the actual size of the lesion and that there is a strong correlation between the presence of M. ulcerans in the margin samples and the surgical distance. Excision with a surgical distance of 25 mm avoided the risk of remaining mycobacteria in this study. However, no recurrences occurred in the patients with M. ulcerans-positive excision margins. The need of postoperative antimycobacterial treatment in these patients remains to be determined.

[Effector influence of oxygen-containing C1 compounds in the cultivation of the methanotrophic bacterial strain GB 25]. / Effektorwirkung von sauerstoffhaltigen C1-Verbindungen bei der Kultivierung des methanotrophen Bakterienstammes GB 25.

Addition of oxygen-containing C1-compounds to chemostat cultures of GB 25 increases both the yield of biomass and the specific growth rate. At optimum concentrations the catalytic activity of these compounds increases with increasing growth rates. Their influence on maintenance coefficients and maximum yield coefficients decreases in the order CH3OH greater than CO2 greater than HCOOH greater than HCHO. This result together with spectrophotometric NADH determinations suggests that the NADH pool determines the balance between the assimilatory and oxidative utilization of formaldehyde.

[Effect of oxygen containing C1 compounds on the growth of methane-assimilating bacteria]. / Einfluss sauerstoffhaltiger C1-Verbindungen auf das Wachstum methanassimilierender Bakterien.

Added C1-compounds of the intermediates methanol, formaldehyde, formate and carbon dioxide show a catalytic effect on the growth rate and cell yield of CH4-assimilating bacteria GB 25 with serine pathway. Maximum stimulation is obtained by added amounts of about 20 mg C1-compound/g bacteria dry matter. The influence of C1-compounds decreases as follows: methanol greater than carbon dioxide greater than formate greater than formaldehyde.