Compression of sub-relativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction

We demonstrate compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching as a result of a velocity chirp, induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs

Theory of coherent transition radiation generated by ellipsoidal electron bunches

We present the theory of coherent transition radiation (CTR) generated by ellipsoidal electron bunches. We calculate analytical expressions for the electric field spectrum, the power spectrum, and the temporal electric field of CTR, generated by cylindrically symmetric ellipsoidal electron bunches with hard and soft edges. This theory is relevant for diagnostics of ellipsoidal electron bunches. Realization of such bunches would solve the problem of space-charge induced emittance degradation

New electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range

We present a method for producing sub-100 fs electron bunches that are suitable for single-shot ultrafast electron diffraction experiments in the 100 keV energy range. A combination of analytical results and state-of-the-art numerical simulations show that it is possible to create 100 keV, 0.1 pC, 20 fs electron bunches with a spotsize smaller than 500 micron and a transverse coherence length of 3 nm, using established technologies in a table-top set-up. The system operates in the space-charge dominated regime to produce energy-correlated bunches that are recompressed by established radio-frequency techniques. With this approach we overcome the Coulomb expansion of the bunch, providing an entirely new ultrafast electron diffraction source concept

Compression of sub-relativistic space-charge-dominated electron bunches for singleshot femtosecond electron diffraction

We demonstrate the compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching by inverting the positive space-charge-induced velocity chirp. This inversion is induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs

A comparison of complications between open abdominal sacrocolpopexy and laparoscopic sacrocolpopexy for the treatment of vault prolapse

Introduction. Sacrocolpopexy is a generally applied treatment for vault prolapse which can be performed laparoscopically or by open laparotomy. Methods. Between October 2007 and December 2012, we performed a multicenter prospective cohort study in 2 university and 4 teaching hospitals in the Netherlands. We included patients with symptomatic posthysterectomy vaginal vault prolapse requiring surgical treatment, who either had abdominal or laparoscopic sacrocolpopexy. We studied surgery related morbidity, which was divided in pre-, peri-, and postoperative characteristics. Results. We studied 85 patients, of whom 42 had open abdominal and 43 laparoscopic sacrocolpopexy. In the laparoscopic sacrocolpopexy group, estimated blood loss was significantly less compared to the abdominal group: 192 mL (±126) versus 77 mL (±182), respectively (P ≤ .001). Furthermore, hospital stay was significantly shorter in the laparoscopic group (4.2 days) as compared to the abdominal group (2.4 days) (P ≤ .001). The overall complication rate was not significantly different (P = .121). However there was a significant difference in favor of the laparoscopic group in peri- and postoperative complications requiring complementary (conservative) treatment and/or extended admittance (RR 0.24 (95%-CI 0.07-0.80), P = .009). Conclusion. Laparoscopic sacrocolpopexy reduces blood loss and hospital stay as compared to abdominal sacrocolpopexy and generates less procedure related morbidity.Anne-Lotte W. M. Coolen, Anique M. J. van Oudheusden, Hugo W. F. van Eijndhoven, Tim P. F. M. van der Heijden, Rutger A. Stokmans, Ben Willem J. Mol, and Marlies Y. Bonger

Wp-2 basic investigation of transition effect

An important goal of the TFAST project was to study the effect of the location of transition in relation to the shock wave on the separation size, shock structure and unsteadiness of the interaction area. Boundary layer tripping (by wire or roughness) and flow control devices (Vortex Generators and cold plasma) were used for boundary layer transition induction. As flow control devices were used here in the laminar boundary layer for the first time, their effectiveness in transition induction was an important outcome. It was intended to determine in what way the application of these techniques induces transition. These methods should have a significantly different effect on boundary layer receptivity, i.e. the transition location. Apart from an improved understanding of operation control methods, the main objective was to localize the transition as far downstream as possible while ensuring a turbulent character of interaction. The final objective, involving all the partners, was to build a physical model of transition control devices. Establishing of such model would simplify the numerical approach to flow cases using such devices. This undertaking has strong support from the industry, which wants to include these control devices in the design process. Unfortunately only one method of streamwise vortices was developed and investigated in the presented study

Influence of short term storage conditions, concentration methods and excipients on extracellular vesicle recovery and function

Extracellular vesicles (EVs) are phospholipid bilayer enclosed vesicles which play an important role in intercellular communication. To date, many studies have focused on therapeutic application of EVs. However, to progress EV applications faster towards the clinic, more information about the physical stability and scalable production of EVs is needed. The goal of this study was to evaluate EV recovery and function after varying several conditions in the isolation process or during storage. Physical stability and recovery rates of EVs were evaluated by measuring EV size, particle and protein yields using nanoparticle tracking analysis, microBCA protein quantification assay and transmission electron microscopy. Western blot analyses of specific EV markers were performed to determine EV yields and purity. EV functionality was tested in an endothelial cell wound healing assay. Higher EV recovery rates were found when using HEPES buffered saline (HBS) as buffer compared to phosphate buffered saline (PBS) during EV isolation. When concentrating EVs, 15 ml spinfilters with a 10 kDa membrane cutoff gave the highest EV recovery. Next, EV storage in polypropylene tubes was shown to be superior compared to glass tubes. The use of protective excipients during EV storage, i.e. bovine serum albumin (BSA) and Tween 20, improved EV preservation without influencing their functionality. Finally, it was shown that both 4 °C and −80 °C are suitable for short term storage of EVs. Together, our results indicate that optimizing buffer compositions, concentrating steps, protective excipients and storage properties may collectively increase EV recovery rates significantly while preserving their functional properties, which accelerates translation of EV-based therapeutics towards clinical application