Adhesion of surfaces mediated by adsorbed particles: Monte Carlo simulations and a general relationship between adsorption isotherms and effective adhesion energies

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.In colloidal and biological systems, interactions between surfaces are often mediated by adsorbed particles or molecules that interconnect the surfaces. In this article, we present a general relationship between the adsorption isotherms of the particles and the effective, particle-mediated adhesion energies of the surfaces. Our relationship is based on the analysis and modeling of detailed data from Monte Carlo simulations. As general properties that should hold for a wide class of adsorption scenarios, we find (i) that the particle-mediated adhesion energies of surfaces are maximal at intermediate bulk concentrations of the particles, and (ii) that the particle coverage in the bound state of the surfaces is twice the coverage in the unbound state at these bulk concentrations.DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interface

Effect of a Common Genetic Variant (p.V444A) in the Bile Salt Export Pump on the Inhibition of Bile Acid Transport by Cholestatic Medications

The bile salt export pump (BSEP) is the primary canalicular transporter responsible for the secretion of bile acids from hepatocytes into bile canaliculi, and inhibition of this transporter has been associated with drug-induced liver injury (DILI). A common variant (rs2287622; p.V444A) in the gene encoding BSEP has been associated with an increased risk of cholestatic DILI. Although p.444V BSEP (reference) and p.444A BSEP (variant) do not differ in their transport kinetics of taurocholic acid (TCA), transport of the more abundant glycocholic acid (GCA) has not been investigated. Importantly, differences in the susceptibility of p.444V and p.444A BSEP to inhibition by drugs causing cholestatic DILI have not been investigated. To address these issues, the transport kinetics of GCA were evaluated by incubating membrane vesicles expressing either p.444V or p.444A BSEP with GCA over a range of concentrations (1, 10, 25, 50, and 100 μM). The abilities of commonly used cholestatic medications to inhibit the transport of TCA and GCA by the reference and variant proteins were compared. Resulting data indicated that GCA transport kinetics for reference and variant BSEP followed Michaelis-Menten kinetics and were not statistically different [ Vmax values of 1132 ± 246 and 959 ± 256 pmol min-1 (mg of protein)-1, respectively, and Km values of 32.7 ± 18.2 and 45.7 ± 25.5 μM, respectively]. There were no statistically significant differences between the reference and variant BSEP in the inhibition of TCA or GCA transport by the cholestatic drugs tested. In conclusion, differential inhibition of TCA or GCA transport cannot account for an association between the variant BSEP and the risk for cholestatic DILI due to the drugs tested

Navigation und Robotik an der Otobasis

Zusammenfassung: Die bildgestützten computerassistierten mikroskopischen Eingriffe an der Otobasis stellen einen seltenen Eingriff in der täglichen Praxis dar. Es handelt sich jedoch um delikate und schwierige minimalinvasive Eingriffe, da die Orientierung im Felsenbein bis zur Felsenbeinspitze oft schwierig ist. Bei Malformationen oder Tumoren sind die normalen anatomischen Landmarken, die dem Chirurgen als Orientierung dienen, häufig nicht vorhanden. Die Navigation, zusammen mit den bildgebenden Verfahren wie CT, MRT und Angiographie, hilft dem Chirurgen, sich bei unübersichtlichen Verhältnissen im Raum zu orientieren, um die Operation auf diese Weise sicherer und z.T. auch schneller durchzuführen. Weltweite einheitliche Indikationen zum Einsatz an der Otobasis fehlen aber. Die navigationsgestützte Miniaturrobotik ist noch in den ersten praktischen Testphase

How Is Variety in Daily Life Related to the Expression of Personality States? An Ambulatory Assessment Study

People differ in the way they live their daily lives. For some people, daily life is characterized by multiple and diverse experiences, while others have more stability and routine in their lives. However, little is known about how variety in daily life relates to the expression of personality states. The present study examined within-person associations between variety in social partners, places, and activities with state expression. Data came from an ambulatory assessment study (N = 962, Mage = 25.49) with four assessments per day over a period of six consecutive days. The results of the multilevel modeling analyses suggest that variety in daily life is associated with some, but not all, state expressions. For instance, on days when participants experienced a greater variety in activities, they reported being less neurotic and conscientious, but also more agreeable. In addition, the links between all social partners, places, and activities with the expression of the state were examined simultaneously to obtain more detailed information on the multifaceted nature of situation-state expression links. We conclude that variety in daily life has both theoretical and empirical relevance for the expression of personality states

The Effect of wake Turbulence Intensity on Transition in a Compressor Cascade

Direct numerical simulations of separating flow along a section at midspan of a low-pressure V103 compressor cascade with periodically incoming wakes were performed. By varying the strength of the wake, its influence on both boundary layer separation and bypass transition were examined. Due to the presence of small-scale three-dimensional fluctuations in the wakes, the flow along the pressure surface undergoes bypass transition. Only in the weak-wake case, the boundary layer reaches a nearly-separated state between impinging wakes. In all simulations, the flow along the suction surface was found to separate. In the simulation with the strong wakes, separation is intermittently suppressed as the periodically passing wakes managed to trigger turbulent spots upstream of the location of separation. As these turbulent spots convect downstream, they locally suppress separation. © 2014 Springer Science+Business Media Dordrecht

Assessment of thermal and hydrolytic stabilities and aqueous solubility of artesunate for formulation studies

For the purpose of establishing the optimum processing parameters and storage conditions associated with nanolipid formulations of the artemisinin derivative artesunate, it was necessary to evaluate the thermal stability and solubility profiles of artesunate in aqueous solutions at various temperatures and pH. The effect of increased temperature and humidity on artesunate was determined by storing samples of the raw material in a climate chamber for 3 months and analyzing these by an established HPLC metho

Development of an auditory implant manipulator for minimally invasive surgical insertion of implantable hearing devices

Abstract Objective: To present the auditory implant manipulator, a navigation-controlled mechanical and electronic system which enables minimally invasive (‘keyhole') transmastoid access to the tympanic cavity. Materials and methods: The auditory implant manipulator is a miniaturised robotic system with five axes of movement and an integrated drill. It can be mounted on the operating table. We evaluated the surgical work field provided by the system, and the work sequence involved, using an anatomical whole head specimen. Results: The work field provided by the auditory implant manipulator is considerably greater than required for conventional mastoidectomy. The work sequence for a keyhole procedure included pre-operative planning, arrangement of equipment, the procedure itself and post-operative analysis. Conclusion: Although system improvements are necessary, our preliminary results indicate that the auditory implant manipulator has the potential to perform keyhole insertion of implantable hearing device

Efficient Generation of Multipotent Mesenchymal Stem Cells from Umbilical Cord Blood in Stroma-Free Liquid Culture

BACKGROUND: Haematopoiesis is sustained by haematopoietic (HSC) and mesenchymal stem cells (MSC). HSC are the precursors for blood cells, whereas marrow, stroma, bone, cartilage, muscle and connective tissues derive from MSC. The generation of MSC from umbilical cord blood (UCB) is possible, but with low and unpredictable success. Here we describe a novel, robust stroma-free dual cell culture system for long-term expansion of primitive UCB-derived MSC. METHODS AND FINDINGS: UCB-derived mononuclear cells (MNC) or selected CD34(+) cells were grown in liquid culture in the presence of serum and cytokines. Out of 32 different culture conditions that have been tested for the efficient expansion of HSC, we identified one condition (DMEM, pooled human AB serum, Flt-3 ligand, SCF, MGDF and IL-6; further denoted as D7) which, besides supporting HSC expansion, successfully enabled long-term expansion of stromal/MSC from 8 out of 8 UCB units (5 MNC-derived and 3 CD34(+) selected cells). Expanded MSC displayed a fibroblast-like morphology, expressed several stromal/MSC-related antigens (CD105, CD73, CD29, CD44, CD133 and Nestin) but were negative for haematopoietic cell markers (CD45, CD34 and CD14). MSC stemness phenotype and their differentiation capacity in vitro before and after high dilution were preserved throughout long-term culture. Even at passage 24 cells remained Nestin(+), CD133(+) and >95% were positive for CD105, CD73, CD29 and CD44 with the capacity to differentiate into mesodermal lineages. Similarly we show that UCB derived MSC express pluripotency stem cell markers despite differences in cell confluency and culture passages. Further, we generated MSC from peripheral blood (PB) MNC of 8 healthy volunteers. In all cases, the resulting MSC expressed MSC-related antigens and showed the capacity to form CFU-F colonies. CONCLUSIONS: This novel stroma-free liquid culture overcomes the existing limitation in obtaining MSC from UCB and PB enabling so far unmet therapeutic applications, which might substantially affect clinical practice

A cAMP-binding ectoprotein in the yeast Saccharomyces cerevisiae

tides 10, 593-595

Measurement of the differential cross section and charge asymmetry for inclusive pp → W\u3csup\u3e±\u3c/sup\u3e + \u3ci\u3eX\u3c/i\u3e production at √\u3ci\u3es\u3c/i\u3e = 8 TeV

The differential cross section and charge asymmetry for inclusive pp → W± + X → μ±ν + X production at √s = 8 TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8 fb−1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10−3 to 10−1