Pump-probe capabilities at the SPB/SFX instrument of the European XFEL

Pump-probe experiments at X-ray free-electron laser (XFEL) facilities are a powerful tool for studying dynamics at ultrafast and longer timescales. Observing the dynamics in diverse scientific cases requires optical laser systems with a wide range of wavelength, flexible pulse sequences and different pulse durations, especially in the pump source. Here, the pump-probe instrumentation available for measurements at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument of the European XFEL is reported. The temporal and spatial stability of this instrumentation is also presented.

Initial observations of the femtosecond timing jitter at the European XFEL

Intense, ultrashort, and high-repetition-rate X-ray pulses, combined with a femtosecond optical laser, allow pump-probe experiments with fast data acquisition and femtosecond time resolution. However, the relative timing of the X-ray pulses and the optical laser pulses can be controlled only to a level of the intrinsic error of the instrument which, without characterization, limits the time resolution of experiments. This limitation inevitably calls for a precise determination of the relative arrival time, which can be used after measurement for sorting and tagging the experimental data to a much finer resolution than it can be controlled to. The observed root-mean-square timing jitter between the X-ray and the optical laser at the SPB/SFX instrument at European XFEL was 308 fs. This first measurement of timing jitter at the European XFEL provides an important step in realizing ultrafast experiments at this novel X-ray source. A method for determining the change in the complex refractive index of samples is also presented.

12 MW peak power from a two-crystal Yb:KYW chirped-pulse oscillator with cavity-dumping

We report on substantial pulse energy increase in Yb:KYW femtosecond laser oscillators by utilizing multiple laser crystals for an enhanced net-gain at higher pump power. The two-crystal oscillator generates pulse energies of 7 µJ at 1 MHz repetition rate which is, to our knowledge the highest energy ever reported from an Yb-doped tungstate fs-laser oscillator. The external pulse compression yields a pulse duration of 416 fs with a peak power of 12 MW being enough for stable white light generation in YAG.

Passively mode-locked and cavity-dumped Yb:KY(WO(4))(2) oscillator with positive dispersion

We demonstrate, what is to our knowledge the first passively mode-locked Ytterbium based solid state high energy laser oscillator operated in the positive dispersion regime. Compared to solitary mode-locking the pulse energy can be increased with even broader spectral bandwidth. With high speed cavity dumping the laser generates 2 muJ-pulses at a 1 MHz repetition rate. The chirped output pulses are compressible down to 420 fs.

Expression of the RNA-binding protein IMP1 correlates with poor prognosis in ovarian carcinoma

The IMP (IGFII mRNA-binding protein) family comprises a group of three RNA-binding proteins involved in the regulation of cytoplasmic mRNA-fate. Recent studies identified IMP proteins as oncofetal factors in various neoplasias, but knowledge of a potential role in ovarian carcinomas is still lacking. The immunohistochemical analysis of 107 ovarian carcinomas, 30 serous borderline tumors of the ovary and five normal ovaries revealed de novo synthesis of IMP1 in 69% of ovarian carcinomas. Elevated IMP1 expression was observed preferentially in high-grade and high-stage cases and was a significant prognostic indicator for reduced recurrence-free and overall survival. Phenotypic studies in ovarian carcinoma-derived ES-2 cells demonstrated that IMP1 knockdown affects proliferation and cell survival. Reduced proliferation was associated with decreased c-myc mRNA half-life, suggesting IMP1 as an oncogenic factor that is involved in promoting elevated proliferation by stabilizing the c-myc mRNA in ovarian carcinoma cells.

Association between tPA therapy and raised early matrix metalloproteinase-9 in acute stroke

BACKGROUND

Matrix metalloproteinase-9 (MMP9) is expressed in acute ischemic stroke and up-regulated by tissue plasminogen activator (tPA) in animal models. The authors investigated plasma MMP9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase (TIMP1), in tPA-treated and -untreated stroke patients.

METHODS

Nonstroke control subjects and consecutive ischemic stroke patients presenting within 8 hours of onset were enrolled. Blood was sampled within 8 hours and at 24 hours, 2 to 5 days and 4 to 6 weeks. MMP9 and TIMP1 were analyzed by ELISA and gel zymography.

RESULTS

Fifty-two cases (26 tPA treated, 26 tPA untreated) and 27 nonstroke control subjects were enrolled. Hyperacute MMP9 was elevated in tPA-treated vs tPA-untreated patients (medians 43 vs 28 ng/mL; p = 0.01). tPA therapy independently predicted hyperacute MMP9 after adjustment for stroke severity, volume, and hemorrhagic transformation (p = 0.01). There was a trend toward lower hyperacute TIMP1 levels in tPA-treated vs tPA-untreated patients (p = 0.06). Hyperacute MMP9 was correlated to poor 3-month modified Rankin Scale outcome (r = 0.58, p = 0.0005).

CONCLUSION

Tissue plasminogen activator independently predicted plasma matrix metalloproteinase-9 (MMP9) in the first 8 hours after human ischemic stroke. As MMP9 may be an important mediator of hemorrhagic transformation, alternative thrombolytic agents or therapeutic MMP9 inhibition may increase the safety profile of acute stroke thrombolysis.

Supercontinuum generation system for optical coherence tomography based on tapered photonic crystal fibre

We report smooth and broad continuum generation using a compact femtosecond Ti:Sapphire laser as a pump source and a tapered photonic crystal fibre as a nonlinear element. Spectral output is optimized for use in optical coherence tomography, providing a maximum longitudinal resolution of 1.5 microm in free space at 809 nm centre wavelength without use of additional spectral filtering.

Continuum generation in a novel photonic crystal fiber for ultrahigh resolution optical coherence tomography at 800 nm and 1300 nm

Ultrahigh resolution optical coherence tomography (OCT) is demonstrated at 800 nm and 1300 nm using continuum generation in a single photonic crystal fiber with a parabolic dispersion profile and two closely spaced zero dispersion wavelengths. Both wavelengths are generated simultaneously by pumping the fiber with ~78 mW average power at 1064 nm in a 52 MHz, 85 fs pulse train from a compact Nd:Glass oscillator. Continuum processes result in a double peak spectrum with > 110 nm and 30 mW average power at 800 nm and > 150 nm and 48 mW at 1300 nm. OCT imaging with < 5 mum resolution in tissue at 1300 nm and < 3 mum resolution at 800 nm is demonstrated. Numerical modeling of propagation was used to predict the spectrum and can be used for further optimization to generate smooth, broad spectra for OCT applications.

Quasi-synchronous pumping of modelocked few-cycle Titanium Sapphire lasers

We investigate the modelocking dynamics of quasi-synchronously pumped, dispersion managed Kerr-lens modelocked Titanium-Sapphire lasers. For the first time, self-starting few-cycle laser pulses with 6 fs pulse duration and ultrabroadband optical spectra are demonstrated without using any intracavity elements like saturable absorbers.

C-band waveguide amplifier produced by femtosecond laser writing

An optical waveguide amplifier fabricated on erbium-ytterbium-doped phosphate glass by direct femtosecond laser writing is demonstrated. The waveguides are manufactured using 1040-nm radiation from a diode-pumped cavity-dumped Yb:KYW oscillator, operating at a 885 kHz repetition rate, with a 350 fs pulse duration. Peak internal gain of 9.2 dB is obtained at 1535 nm, with a minimum internal gain of 5.2 dB at 1565 nm. Relatively low insertion losses of 1.9 dB enable for the first time an appreciable net gain in the full C-band of optical communications.

High speed electro-optical cavity dumping of mode-locked laser oscillators

High speed electro-optical cavity dumping is demonstrated with diode-pumped mode-locked laser oscillators, namely a femtosecond Yb:glass and a picosecond Nd:YVO4 oscillator. Repetition frequencies exceeding 1MHz are obtained with pulse energies of more than 300nJ /1 microJ. Being compact and easy to operate light sources, these laser systems open up various scientific and industrial applications.

Diode-pumped, ultrafast, multi-octave supercontinuum source at repetition rates between 500 kHz and 20 MHz using Yb:glass lasers and tapered fibers

We present a compact, all diode-pumped supercontinuum source based on a SESAM mode-locked Yb:glass oscillator at 1040 nm and a tapered fiber. The oscillator has a repetition rate of 20 MHz, a pulse duration of 200 fs, and a maximum pulse energy of about 15 nJ. This system delivers an 1100 nm broad spectrum with an output power of more than 100 mW. Decreasing the repetition rate to 500 kHz by cavity-dumping results in a supercontinuum with a high pulse energy of about 50 nJ. Furthermore, using the frequency-doubled output of this laser at 520 nm with 300 fs pulse duration resulted in supercontinua in the near-UV and visible spectral region. We compare the experimental spectra with theoretical simulations.

Er:Yb-doped waveguide laser fabricated by femtosecond laser pulses

Laser action is demonstrated in a 20-mm-long waveguide fabricated on an Er:Yb-doped phosphate glass by femtosecond laser pulses. An output power of 1.7 mW with approximately 300 mW of pump power coupled into the waveguide is obtained at 1533.5 nm. Waveguides are manufactured with the 520-nm radiation from a frequency-doubled, diode-pumped, cavity-dumped Yb:glass laser operating at a 166-KHz repetition rate, with a 300-fs pulse duration.

Optical waveguide writing with a diode-pumped femtosecond oscillator

Optical waveguide writing is demonstrated by means of a diode-pumped cavity-dumped Yb:glass femtosecond laser oscillator with a pulse energy of 270 nJ at a 166-kHz repetition rate. Waveguides realized on an Er:Yb-doped phosphate glass are almost perfectly mode matched to standard single-mode fibers at 1.55 microm and show a 1.2-dB net gain in a standard telecommunications amplifier setup. Waveguide writing with a compact femtosecond laser oscillator is an important step toward introducing this technique into an industrial context.

Period doubling and deterministic chaos in continuously pumped regenerative amplifiers

Multi-energy and chaotic pulse energy output from a continuously pumped regenerative amplifier is observed for dumping rates around the inverse upper state lifetime of the gain medium. The relevant regimes of operation are analyzed numerically and experimentally in a diode-pumped Yb:glass regenerative amplifier. The boundaries between stable and unstable pulsing are identified and stability criteria in dependence on the amplifier gate length and pump power are discussed.

[Effect of graduate education on complication rate and costs of hip prosthesis implantation]

PURPOSE

We studied the effect of surgical experience with regard to complications and costs after 3290 primary total hip arthroplasties (diagnosis: osteoarthritis).

METHODS

We retrospectively analysed duration of clinical treatment and anaesthesia, blood loss, number of banked blood and perioperative complications (fractures of the shaft and acetabulum, dislocations, peripheral nerve injuries, thrombosis of the deep veins, embolism and deep wound infections) related to the experience of the surgeon (junior surgeons in comparison to the consultant) after 3290 primary THA's from 1974 to 1997. Cost analysis was performed by measurement of time and material expenditure.

RESULTS

39.2% of all operations were performed by junior surgeons. This number emphasizes the realisation of the order of education in our clinic. Both groups showed just few differences in number of duration of clinical treatment, banked blood, nerve leasions and embolism. We found statistically not significant increased rates of fractures and dislocations in the THA's performed by an unexperienced surgeon, however the rates decreased the last 14 years. Significantly higher rates of deep wound infection at the beginning decreased in the last 9 years to the level of experienced surgeons. Due to longer operation times, we calculated higher expenses of DM 85 per case in the group of junior surgeons.

CONCLUSIONS

Using an educational program, carried out with an experienced surgeon, there is nearly no additional risk for the patient regarding the complication rates in THA's. However, there are higher financial expenses that have to be calculated.

Dextrin as excipient in pharmaceutical preparations

The addition of commercial dextrins to aqueous solvents in thin layer chromatography on cellulose increases the Rf values of azodyes such as methyl orange. The increase is less than with cyclodextrins but shows that dextrins also form supramolecular complexes. This should be considered when dextrins are used as "inert" excipients in pharmacy.

[Complete dislocation of the polyethylene inlay after internal hemipelvectomy and individually fitted tumor endoprosthesis]

We report about an exceptional complication after internal hemipelvectomy and replacement of the defect with a custom-made endoprosthesis. A complete luxation of the PE-inlay out of the metal cup occurred. Radiologically we assumed a luxation of the femoral head in dorsal direction. Revision after a failed attempt of closed reposition showed a complete luxation of the inlay, which was caused by deficient fixation in the acetabular component. The absence of a contrast wire in the PE-inlay delayed the right diagnosis and made it difficult to find the dislocated inlay in the large wound.

MIA, a novel serum marker for progression of malignant melanoma

MIA was isolated previously as a small soluble protein secreted from malignant melanoma cell lines in vitro. Highly restricted expression patterns in melanocytic tumors were identified in vivo. We therefore quantitated serum levels of MIA protein by means of a non-radioactive ELISA and investigated whether MIA provides clinically relevant parameters in patients with malignant melanomas. Here we report enhanced MIA serum levels in 13% and 23% of patients with stage I and II disease, respectively, and in 100% with stage III or IV disease. Response to therapy in stage IV disease correlated with changes in MIA serum levels and surgical removal of metastases led to normalization of serum values. Repeated measuring of sera from 350 patients with a history of stage I or II melanoma during follow-up, we detected 32 patients developing positive MIA values. At the time of serum analysis 15 of them had developed metastases and one presented with metastatic disease 6 months later. In conclusion, MIA represents a novel serum marker for systemic malignant melanoma revealing the highest sensitivity and specificity among currently available markers.

[Quality and management of preoperative patient information. Results of conventional and computer based documentation]

INTRODUCTION

Analysis of the quality of different modes of preoperative information management on the example of primary total hip arthroplasty. Comparison between a since 10 years used, computer based system and a conventional procedure with additional hand-written notes.

METHODS

Retrospective analysis of respectively 50 with conventional and computer based system written preoperative patient information. The completeness of the documentation is examined according to the demands of current judgement.

RESULTS

The results confirm, independent from the level of education, a complete documentation of all risks by applying the computer based system, whereas the conventional method leads to considerable lacks of documentation.

DISCUSSION

The computer based system guarantees a high quality of preoperative patient information which cannot be obtained by the conventional method and therefore offers a protection against unjustified claims of liability.

Reaction of 3-deoxypentosulose with N-methyl- and N,N-dimethylguanidine as model reagents for protein-bound arginine and for creatine

Deoxyosones are established key-intermediates in Maillard processes. Due to their dicarbonyl structure, they undergo condensation to form heterocyclic compounds with guanidine derivatives. In biological systems, guanidino functions are present in protein-bound arginine moieties as well as in creatine. The reactivity of such structures towards 3-deoxypentosulose is investigated with N-methyl- and N,N-dimethylguanidine as model substrates. Two diastereoisomers each are isolated from both reactions; they have been characterized unequivocally, respectively, as 4-(2,3-dihydroxypropyl)-2-N-methylamino-2-imidazoline-5-one and 4-hydroxy-5-(2,3-dihydroxypropyl)-2-(N,N-dimethylamino)-5H-imidazole. In aqueous medium as well as in the crystalline state, both diastereoisomer pairs exist in different tautomeric forms.

Reactive Maillard intermediates leading to coloured products-5-hydroxymethyl- and 5-(1,2-dihydroxyethyl)-3(2H)-furanone

In the course of the Maillard reaction, labile sugar degradation products are formed that are susceptible to secondary reactions and therefore have a decisive influence on the product spectrum. Such reactive intermediates may be transformed into stable derivatives with trapping reagents, and thus be protected from further reactions. Secondary processes may also be forestalled if the primary products are removed from the reaction mixture by high-vacuum distillation. By this procedure, 5-hydroxymethyl- and 5-(1,2-dihydroxyethyl)-3(2H)-furanone have been identified directly from Maillard reaction mixtures for the first time. The activated methylene group of these 3(2H)-furanones can easily enter into condensation reactions. The coloured condensation products in turn react with primary amines to pyrrolinone derivatives, which may also contribute to the colouring observed in non-enzymatic browning.

Adsorption chromatography on cellulose. IV. Separation of D- and L-tryptophan and D- and L-methyltryptophan on cellulose with aqueous solvents

Differences in RF values between D- and L-tryptophan on cellulose paper, developed with water, were observed already in 1954 and now several variables of this separation, such as modifications to the tryptophan molecule, the temperature and salting-out have been examined. Differences were found in the mechanism of the process compared with the systems described by Yuasa et al. [Chromatographia, 21 (1986) 79], who separated amino acid enantiomers on cellulose with pyridine-ethanol-water mixtures.

The role of chromatography and electrophoresis in biomedical sciences

Various facets of the history of clinical chromatography are considered, with emphasis on their application to the present state of the art. The work of Goppelsroeder on capillary analysis is reviewed, followed by a discussion of C.E. Dent's work on aminoacidurias, Lato's thin-layer chromatographic studies of sugars in urine, Ian Bush's approach to automated chromatography, as well as the extensive possibilities of high-voltage electrophoresis shown by Clotten and Clotten. It is interesting that none of these methods has been applied extensively in diagnostic work. Capillary electrophoresis, which was developed by Hjertén in 1969, seems to have gained new interest recently. At present, although it seems obvious that chromatographic methods could solve numerous diagnostic problems, surprisingly little work is being done outside the larger hospital laboratories. Some of the reasons for this situation are discussed, as are the future prospects of the Biomedical Applications section of the Journal of Chromatography.

Adsorption chromatography on cellulose. II. Separations of aromatic amino acids, biogenic amines, alkaloids, dyes and phenols and determination of hydrophobic constants

Separations of amines, phenols, alkaloids, etc., using cellulose papers or thin layers with aqueous ammonium sulphate as eluent are reported. These separations illustrate that excellent analytical separations are possible and provide data for the study of the mechanism of adsorption on cellulose from aqueous solutions.