Experimental capabilities for liquid jet samples at sub-MHz rates at the FXE Instrument at European XFEL.

The Femtosecond X-ray Experiments (FXE) instrument at the European X-ray Free-Electron Laser (EuXFEL) provides an optimized platform for investigations of ultrafast physical, chemical and biological processes. It operates in the energy range 4.7-20 keV accommodating flexible and versatile environments for a wide range of samples using diverse ultrafast X-ray spectroscopic, scattering and diffraction techniques. FXE is particularly suitable for experiments taking advantage of the sub-MHz repetition rates provided by the EuXFEL. In this paper a dedicated setup for studies on ultrafast biological and chemical dynamics in solution phase at sub-MHz rates at FXE is presented. Particular emphasis on the different liquid jet sample delivery options and their performance is given. Our portfolio of high-speed jets compatible with sub-MHz experiments includes cylindrical jets, gas dynamic virtual nozzles and flat jets. The capability to perform multi-color X-ray emission spectroscopy (XES) experiments is illustrated by a set of measurements using the dispersive X-ray spectrometer in von Hamos geometry. Static XES data collected using a multi-crystal scanning Johann-type spectrometer are also presented. A few examples of experimental results on ultrafast time-resolved X-ray emission spectroscopy and wide-angle X-ray scattering at sub-MHz pulse repetition rates are given.

An unexpectedly low oscillator strength as the origin of the Fe XVII emission problem.

Highly charged iron (Fe(16+), here referred to as Fe XVII) produces some of the brightest X-ray emission lines from hot astrophysical objects, including galaxy clusters and stellar coronae, and it dominates the emission of the Sun at wavelengths near 15 ångströms. The Fe XVII spectrum is, however, poorly fitted by even the best astrophysical models. A particular problem has been that the intensity of the strongest Fe XVII line is generally weaker than predicted. This has affected the interpretation of observations by the Chandra and XMM-Newton orbiting X-ray missions, fuelling a continuing controversy over whether this discrepancy is caused by incomplete modelling of the plasma environment in these objects or by shortcomings in the treatment of the underlying atomic physics. Here we report the results of an experiment in which a target of iron ions was induced to fluoresce by subjecting it to femtosecond X-ray pulses from a free-electron laser; our aim was to isolate a key aspect of the quantum mechanical description of the line emission. Surprisingly, we find a relative oscillator strength that is unexpectedly low, differing by 3.6σ from the best quantum mechanical calculations. Our measurements suggest that the poor agreement is rooted in the quality of the underlying atomic wavefunctions rather than in insufficient modelling of collisional processes.

Resonant and near-threshold photoionization cross sections of Fe14+.

Photoionization (PI) of Fe14+ in the range from 450 to 1100 eV was measured at the BESSY II storage ring using an electron beam ion trap achieving high target-ion area densities of 10(10) cm(-2). Photoabsorption by this ion is observed in astrophysical spectra and plasmas, but until now cross sections and resonance energies could only be provided by calculations. We reach a resolving power E/ΔE of at least 6500, outstanding in the present energy range, which enables benchmarking and improving the most advanced theories for PI of ions in high charge states.

[Tests on the bactericidal effectiveness of iodophor A in the halls of a pig-fattening station]. / Overení baktericidní úcinnosti jodoforu a v pavilónech výkrmny prasat

In the halls of the pig fattening house the bactericidal effectiveness of cold water solutions of Czechoslovakia-made Jodofor A and the product of the Ciba-Geigy company Iosan was tested and compared with the effectiveness of Chloramin B used in a water solution at the temperature of 50 to 60 degrees C. The solutions were applied by fine spraying at the rate of 0.5 lt. per 1 m2 of area. After one hour the spray was applied again at the same rate. One hour after the last Jodofor spray and two hours after the last Chloramin B spray, smears were collected from the disinfected surfaces. The examination included the detection of coliform germs, germs of the Micrococcaceae family, and the determination of the total number of germs. On the whole, 384 smears were examined in four separate trials. The application of Jodofor A in 2% concentrations, after mechanical average-quality purification, did not give acceptable results, in comparison with the solution of Cloramin B. Only when solutions of Jodofor A and Iosan were used in 3% concentration after perfect mechanical purification, satisfactory results were obtained (with the exception of plaster and painted wood), in comparison with the Chloramin B solution. Better disinfectibility was found in aluminium sheet, terracotta, concrete, and metal, as distinct from plaster and painted wood. The comparison of Jodofor A with abroad-male Iosan indicates that Jodofor has the same or a better bactericidal effect than Iosan in all indices. Due to its bactericidal effect, Jodofor A is a suitable disinfectant for preventive disinfection of farm animal houses. In order to achieve results corresponding to those provided by 2% solutions of Chloramin B it is necessary to use at least 3% concentration of Jodofor A. Good mechanical purification is a basic prerequisite for its effectiveness.

[Bactericidal effect of iodophors of Czechoslovak origin on support materials]. / Baktericidní úcinnost jodoforu ceskoslovenské výroby na nosicích

The bactericidal effectiveness of Jodofor A and Jodofor B produced in Czechoslovakia was tested on carriers (stoneware, concrete, brick, wood, aluminium sheet) contaminated with E. coli and St. aureus. The two Czechoslovak products were compared with Iosan produced by the Ciba-Geigy Comp. Cold water solutions of iodophores were applied in fine spray to horizontal and vertical carriers at two stages with a one-hour interval; the over-all application rate was 1 lt. of solution per 1 m-2 of area. One-hour exposure time from the last application was respected in all cases. On carriers contaminated with E. coli the microorganisms were totally killed by a 1.5% water solution of Jodofor A and Iosam. In Jodofor B the same effect was achieved only with the 2.5% water solution. In St. aureus-contaminated carriers a 100% disinfecting effect was obtained with a 2% water solution of Jodofor A and Iosan and witha 2.5% solution of Jodofor B. Different effectiveness in the disinfectibility of different materials was suggested, and the effect was not found dependent on the position of the material disinfected (vertical, horizontal positions). This testifies to quite a rapid disinfecting effect of iodophores. No large differences in the overall bactericidal effectiveness between Jodofor A and Iosan (Ciba-Geigy) were found either in the evaluation of 100% disinfecting effect or in the use of lower concentrations which only reduced the number of germs surviving on carriers. The effectiveness of Jodofor B was somewhat lower.

[Bactericidal effect of Dikonit]. / Baktericidní úcinok Dikonitu

The research centre of the Lachema nat Bohumín has developed new disinfectants with active chlorine on the basis of chlorinated derivatives of cyanuric acid. According to the physical and chemical properties, Dikon (sodium dichlorisocyanurate) was chosen as the best of these products; Later on, Dikon was given the trade mark Dikonit. Its minimum content of active chlorine is 55%. The purpose of the work was to test its bactericidal effect and to compare it with the effect of chloramin B. Tests on carriers and under practical conditions have demonstrated that, with the same content of active chlorine in solutions in practical use, Dikonit has almost the same bactericidal effect as Chloramin B produced so far. Due to this good bactericidal effect, Dikonit is a suitable means for prophylactic and focal disinfection in animal production and provides a good enrichment of the disinfectants based on active chlorine and produced in Czechoslovakia. It is recommended for prophylactic disinfection to use 1% solutions of Dikonit which are able to give the same effect in all parameters as warm solutions of 2-per-cent Chloramin B. The effective concentration to be used for focal disinfections can be deduced only approximately from the resistance of the infective agent with respect to the concentrations of Chloramin B, recommended as yet. An exact determination of the effective concentration would require experimental verification.

[Effectiveness of environmental disinfection with formalin aerosol]. / Ucinnost prostorové aerosolové dezinfekce formalinem.

The effectiveness was tested of preventive disinfection of pig-fattening houses with formalin, applied as aerosol with the Swingfog SN 100 apparatus. The effectiveness of this treatment was evaluated according to the proportion of smears containing lactoso-positive micro-organisms, expressed as a percentage of the total number of smears, and according to the reduction of contamination with E. coli and St. aureus on wooden or aluminium carriers. The effectiveness was found to be good and the treatment is recommended as suitable for the preventive disinfection of stables. However, the following procedure should be strictly observed: Before disinfection the stables must be thoroughly mechanically cleansed, dried, and well closed to be air-tight. The air temperature in these premises should not be lower than 12 degrees C. Formalin (with a minimum content of 40% of formaldehyde) should be applied at a rate of at least 10 ml per 1 m3 of space and the agent should be diluted with water at 1 : 1 ratio prior to use. The aerosol should be produced by the Swingfog SN 100 generator, adjusted to apply about 40 1 of the solution per hour. The maximum space treated from one place should be limited to 500 m3. The exposure time should be at least 16 hours.

[Control of disinfection with formaldehyde]. / Kontrola dezinfekce formaldehydem

The reliability of a simple method of formaldehyde disinfection control, based on the colour intensity of End's agar or sulphite agar, was tested in a sealed fume chamber 1.2 cubic metres in size at a constant air temperature (21 degrees C) and at a 40-per-cent or 95-per-cent humidity. The effect of formaldehyde concentration and air humidity was examined, as exerted on bactericidal effectiveness and on the colour intensity of the mentioned media. Air humidity proved to be highly important: together with formaldehyde concentration and exposure time, air humidity is the decisive factor underlying the final effect of disinfection if due temperature is maintained. The intensity of the colouring of End's agar or sulphite agar was found to depend mainly on concentration and slightly on air humidity. Hence it is recommended that this simple control should be used only for the testing of a good sealing of the disinfected space underlying the effect of the active concentration of formaldehyde for the necessary exposure time. End's agar, produced by the Imuna National Corporation, Sarisské Michal'any, gave better results. It is considered necessary for an estimation of formaldehyde disinfection effectiveness to record, at the same time, the humidity and temperature of the air in the disinfected space. In our trials at a 95-per-cent humidity level, E. coli was totally devitalized on carriers disinfected with formaldehyde developed from 25 ml formaline and St. aureus with formaldehyde developed from more than 50 ml formaline per 1 cubic metre of space. When the air humidity level was 40% the total devitalization of the mentioned bacterial strains was not achieved even with formaldehyde concentration developed from 75 ml formaline per 1 cubic metre of space.

[Survival of bacteria on zinc-coated and aluminum materials]. / Prezívání bakterií na pozinkovaném a hliníkovém materiálu.

The survival of St. aureus. E. coli, and of salmonellae was tested without any protein error and with it on new galvanized and with disinfection disturbed plate and compared with the survival of these microorganisms on new aluminous plate which was considered to be inert. The investigation by means of the impression method lasted for seven days. The growth of the microorganisms was evaluated according to the index of their survival. A distinct oligodynamic effect of the galvanized plate was proved especially on gram-negative bacteria. The effectiveness increased by a disturbing of these plates with a long-term disinfection in a concentrated solution of chloramine BS. An antimicrobial effect was recorded also in aluminous plates disturbed by disinfection. On both kinds of plate the effectiveness was lowered by a protein error--by an adding of blood serum to the broth suspensions.

[Various indices of microclimate in the newly built and re-adapted stables for race horses]. / Nekteré ukazatele mikroklimatu v nových a adaptovaných stájích sportovních koní

A study was performed to examine microclimate in 14 stables belonging to 10 horsemen's teams and clubs; five of these houses were new-built. In five race-horse stables housing 16 horses each, on an average, where the optimum air temperature ranged from 10 degrees C to 12 degrees C, measurements and examinations were performed in the winter period and the following results were obtained: space per 1 horse housed 42.9 plus or minus 8.7 m-3, relative air humidity 74.3 plus or minus 3.8%, CO2 concentration 0.175 plus or minus 0.027%, NH3 concentration 0.00135 plus or minus 0.00044%. A large majority of horse stables under our conditions lack suitable ventilating equipment for winter and for cold periods. Together with the present-day building technology and with excessive space of box-type houses, this implies that microclimate conditions are unsuitable and harmful to health; in particular, this is true of cold and wet conditions. In the existing stables this problem can be solved by additional heating, preferably with the hot-air system. It is necessary that horse stables should have good thermal-insulation characteristics, with plastered brick walls 45 cm in thickness and with thermally insulated loft. Floors must be solid, hard, and plane. Modern building technology and new materials must secure all the required parameters, with due respect to all factors constituting microclimate and to purposeful layout of race horse stables. It appears desirable to issue a state standard for the construction of horse stables.

High-precision laser-assisted absolute determination of x-ray diffraction angles.

A novel technique for absolute wavelength determination in high-precision crystal x-ray spectroscopy recently introduced has been upgraded reaching unprecedented accuracies. The method combines visible laser beams with the Bond method, where Bragg angles (θ and -θ) are determined without any x-ray reference lines. Using flat crystals this technique makes absolute x-ray wavelength measurements feasible even at low x-ray fluxes. The upgraded spectrometer has been used in combination with first experiments on the 1s2p(1)P(1) → 1s(2)(1)S(0) w-line in He-like argon. By resolving a minute curvature of the x-ray lines the accuracy reaches there the best ever reported value of 1.5 ppm. The result is sensitive to predicted second-order QED contributions at the level of two-electron screening and two-photon radiative diagrams and will allow for the first time to benchmark predicted binding energies for He-like ions at this level of precision.

Testing QED screening and two-loop contributions with He-Like ions.

We report wavelength measurements of H-like and He-like ions obtained with a novel x-ray spectrometer at the Heidelberg Electron Beam Ion Trap. The experimental uncertainty for the Lyman-alpha1 wavelength in Cl16+ is reduced by a factor of 3 and, as expected, excellent agreement with theory is maintained. For the resonance line in He-like Ar16+, an uncertainty of only deltalambda/lambda=2x10(-6) was achieved. This is the most precise x-ray wavelength reported for highly charged ions to date, and allows to test recent predictions on QED two-electron and two-photon radiative corrections for He-like ions. The results also point to the advantages of establishing absolute x-ray wavelength standards using Lyman-alpha transitions (in the present case Ar17+ Lyman-alpha1) to supersede the current ones.