Surface stress and shape relaxation of gelling droplets.

Solidification is a heterogeneous transformation from liquid to solid, which usually combines transport, phase transition and mechanical strain. Predicting the shapes resulting from such a complex process is fascinating and has a wide range of implications from morphogenesis in biological tissues to industrial processes. For soft solids initially at equilibrium, elastic stresses, whether tensile or compressive, can be induced by heterogeneous volumetric deformations of the material. These stresses trigger surface instabilities leading to variations of curvature and shape of the solids. In this article, we study the shape evolution of elongated droplets of polymer and particle suspensions undergoing a solidification process caused by the inward diffusion of a gelling agent from the surface. We show experimentally and numerically that there appears a layer of gelled material growing at the surface. Due to volume contraction, this layer induces tensile stresses and drives a flow in the ungelled liquid core, resulting in the relaxation of the droplets toward spherical shapes. Over time, the thickness of this elastic membrane grows, hence the bending stiffness required to change its shape eventually balances the surface stresses, which arrests the relaxation process. These results provide general rules to understand the shape of solidifying materials combining both tension and bending driven deformations.

[Living Donor Liver Transplantation - Past and Present]. / Lebertransplantation mit Lebendspende ­ Historie und Gegenwart.

Since the first living donor liver transplantations at the end of the 1980s, this transplantation technique has developed as an established tool within the modern transplantation medicine. Especially in Asia, the majority of liver transplantation is performed through living donation, mainly for religious reasons. Liver grafts for adult recipients are mainly the right liver lobe of the donor, for paediatric recipients mainly the left lateral lobe. In some cases, the living donor liver transplantation is realised from two different donors for one recipient, the so-called "dual graft" transplantation. This article summarises the history of living donor liver transplantation up to the current status of this transplantation procedure worldwide.

Surface Fraction Dependence of Contact Angles Induced by Kinks in the Triple Line.

On periodic superhydrophobic surfaces the receding contact angle often scales with the surface fraction, as expected from a simple rule of mixture, the Cassie relation. However, it has been argued that energy averaging breaks down owing to line pinning, and that line fraction scaling should apply instead. From experiments and simulations we show that proper inclusion of triple line defects introduce surface fraction scaling in the line depinning threshold. In contrast to the Cassie relation and in agreement with the data, this dependence is strongly nonlinear due to triple line elasticity.

In situ Brillouin study of sodium alumino silicate glasses under pressure.

The in situ elastic and plastic behaviors of sodium aluminosilicate glasses with different degrees of depolymerization were analyzed using Brillouin spectroscopy. The observed elastic anomaly progressively vanished with depolymerization. The densification process appears to be different from that observed in pure silica glass. In the plastic regime of densified glasses hysteresis loops were observed and related to modification of the local silicon environment facilitated by the addition of sodium.

Slip dynamics at a patterned rubber/glass interface during stick-slip motions.

We report on an experimental study of heterogeneous slip instabilities generated during stick-slip motions at a contact interface between a smooth rubber substrate and a patterned glass lens. Using a sol-gel process, the glass lens is patterned with a lattice of parallel ridges (wavelength, 1.6 µm, amplitude 0.35 µm). Friction experiments using this patterned surface result in the systematic occurrence of stick-slip motions over three orders of magnitude in the imposed driving velocity while stable friction is achieved with a smooth surface. Using a contact imaging method, real-time displacement fields are measured at the surface of the rubber substrate. Stick-slip motions are found to involve the localized propagation of transverse interface shear cracks whose velocity is observed to be remarkably independent on the driving velocity.

18F-FDG-uptake of hepatocellular carcinoma on PET predicts microvascular tumor invasion in liver transplant patients.

Vascular invasion of hepatocellular carcinoma (HCC) is a major risk factor for poor outcome after liver transplantation (LT). The aim of this retrospective analysis was to assess the value of preoperative positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) in liver transplant candidates with HCC for predicting microvascular tumor invasion (MVI) and posttransplant tumor recurrence. Forty-two patients underwent LT for HCC after PET evaluation. Sixteen patients had an increased (18)F-FDG tumor uptake on preoperative PET scans (PET +), while 26 recipients revealed negative PET findings (PET-) pre-LT. PET- recipients demonstrated a significantly better 3-year recurrence-free survival (93%) than PET + patients (35%, p < 0.001). HCC recurrence rate was 50% in the PET + group, and 3.8% in the PET-population (p < 0.001). PET + status was identified as independent predictor of MVI [hazard ratio: 13.4]. Patients with advanced PET negative tumors and patients with HCC meeting the Milan criteria had a comparable 3-year-recurrence-free survival (80% vs. 94%, p = 0.6). Increased (18)F-FDG uptake on PET is predictive for MVI and tumor recurrence after LT for HCC. Its application may identify eligible liver transplant candidates with tumors beyond the Milan criteria.

Optical control of electrons during electron transfer.

The dynamics of electron transfer reactions in solution can be controlled with the use of a sequence of femtosecond laser pulses. In the charge transfer to solvent (CTTS) reaction of sodide (Na-) in tetrahydrofuran, an initial light pulse launched the CTTS reaction, ejecting an electron into either an immediate or a solvent-separated Na0:solvated electron contact pair. A second pulse was used to excite the electrons in the contact pairs, and a third pulse monitored the amount of Na- produced through the back electron transfer. Excitation of the electrons in immediate contact pairs shut off the back electron transfer, whereas excitation of the electrons in solvent-separated pairs both enhanced and hindered the back electron transfer.

Scanning thermal microscopy and Raman analysis of bulk fused silica exposed to low-energy femtosecond laser pulses.

Low energy femtosecond laser pulses locally increase the refractive index and the hydro-fluoric acid etching rate of fused silica. These phenomena form the basis of a direct-write method to fabricate integrated glass devices that are of particular interest for optofluidics and optomechanical applications. Yet the underlying physical mechanism behind these effects remains elusive, especially the role of the laser polarization. Using Scanning Thermal Microscope and Raman spectrometer we observe in laser affected zones, a localized sharp decrease of the thermal conductivity correlated with an increased presence of low-number SiO(2) cycles. In addition, we find that a high correlation exists between the amount of structural changes and the decrease of thermal conductivity. Furthermore, sub-wavelength periodic patterns are detected for high peak power exposures. Finally, our findings indicate that, to date, the localized densification induced by femtosecond laser pulses remains well below the theoretical value achievable in mechanically densified silica.

Oral tacrolimus bioavailability is increased after right split liver transplantation.

OBJECTIVE: Tacrolimus (Tac) is mainly metabolized in the liver. The aim of this trial was to analyze Tac bioavailability after partial liver transplantation. PATIENTS AND METHODS: A total of 33 patients after right split liver grafting (n=8 living related, LRLT; n=8 cadaver split, CS) or full-size liver transplantation (n=17, FS) were included in this trial. All of them received Tac perorally with an initial dose of 2x5 mg/d. Dose adjustment was performed according to the Tac trough level (T0) with an initial target T0 levels of 12 to 15 ng/mL. RESULTS: The time to reach target T0 levels tended to be lower (P=.05) in the split liver groups (LRLT: 2.8+/-1.6 days; CS: 2.1+/-0.9 days; FS: 4.5+/-3.2 days). In addition, mean Tac dose to maintain the target T0 level was significantly decreased (P=.01) in the split liver cohorts (LRLT: 5.8+/-1.1 mg/d; CS: 5.5+/-2.5 mg/d; FS: 9.8+/-3.9 mg/d). Only graft weight/standard liver volume ratio (r=.566, P=.02) and graft weight/body weight ratio (r=.709, P=.002) showed significant correlations with Tac maintenance doses in the split liver group. CONCLUSIONS: Peroral Tac bioavailability was significantly higher after partial liver transplantation using the right hepatic lobe compared with full-size transplants. The volume of the split liver graft highly correlated with Tac maintenance therapy and should be used to calculate the most appropriate initial posttransplantation Tac dose.

Cross-condensation and particle growth in aqueous silane mixtures at low concentration.

We have observed the condensation of a mixture of gamma-glycidoxypropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane in dilute aqueous solutions. NMR and IR spectroscopy have allowed to follow the condensation process in the mixture, which is noticeably enhanced and proceeds faster than for each silane on its own. Cross-condensation between the two silanes was evidenced. When the hydrophilic aminosilane is in excess, the condensation, as evidenced by dynamic light scattering, proceeds toward gel formation because the oligomers formed are essentially hydrophilic. When the more hydrophobic epoxysilane is in excess, oligomer growth proceeds slowly and results in a destabilization of the solution: due to their hydrophobic character, the oligomers formed coalesce suddenly into 200-nm-diameter aggregates. Coatings deposited from such solutions with high epoxysilane content can be used to strengthen glass. We show that the progress of condensation in solution results in a wetting transition during deposition of the silane film on glass by dip coating. The production of increasingly hydrophobic oligomers as the reaction time increases results in adsorption of more hydrophobic aggregates at the surface, which eventually leads to dewetting of the film: in the absence of film, glass strengthening disappears.

Impact of pressure on plastic yield in amorphous solids with open structure.

Plasticity in amorphous silica is unusual: The yield stress decreases with hydrostatic pressure, in contrast to the Mohr-Coulomb response commonly found in more compact materials such as bulk metallic glasses. To better understand this response, we have carried out molecular dynamics simulations of plastic response in a model glass with open structure. The simulations reproduce the anomalous dependence of yield stress with pressure and also correctly predict that the plastic response turns to normal once the material has been fully compacted. We also show that the overall shape of the yield surface is consistent with a quadratic behavior predicted assuming local buckling of the structure, a point of view that fits well into the present understanding of the deformation mechanisms of amorphous silica. The results also confirm that free volume is an adequate internal variable for a continuum scale description of the plastic response of amorphous silica. Finally, we also investigate the long-range correlations between rearrangement events. We find that strong intermittency is observed when the structure remains open, while compaction results in more homogeneous rearrangements. These findings are in agreement with recent results on the effect of compression on the middle range order in silicate glasses and also suggest that the well-known volume recovery of densified silica at relatively low temperatures is in fact a form of aging.

The hematopoietic stem cell compartments in mice during and after long-term inhalation of three doses of benzene.

Female BDF1 mice were exposed for 16 weeks to airborne concentrations of 100, 300, and 900 ppm of benzene, 6 h per day, 5 days per week. Bone marrow hemopoietic stem cell compartments and peripheral blood cell counts were studied using clonal assays and standard methods. Dose-dependent depressive effects were observed on all stem cell compartments. Only the erythroid colony-forming units (CFU-E) compartment was depressed during exposures to 100 ppm; CFU-E were more sensitive than the erythroid burst-forming units (BFU-E), spleen CFU (CFU-S), or G-M CFU (CFU-C) during exposure to 300 ppm or 900 ppm. Lymphocytopenia was observed in the peripheral blood. After benzene-free intervals, a regeneration of lymphocyte numbers and slow normalization of stem cell numbers was seen. Complete recovery from the 16 weeks exposure to 300 ppm was seen between 73 and 185 days.

The influence of benzene on the erythroid cell system in mice.

Female BDF1 mice were exposed up to 8 weeks to airborne concentrations of 100, 300, and 900 ppm of benzene, 6 h/day, 5 days/week. The erythropoietic cell compartment in the bone marrow and the peripheral blood was studied using the erythroid burst-forming unit (BFU-E) and erythroid colony-forming unit (CFU-E) assays, the incorporation of 59Fe, and standard methods. In the peripheral blood only a slight anemia was observed. In the bone marrow, however, a considerable decrease of CFU-E numbers was seen, the CFU-E being more depressed than the BFU-E numbers. In bone marrow smears a variable content of erythroblasts was found. The 59Fe kinetics showed an enhanced turnover within the erythron, suggesting the decrease in transit time as a compensating mechanism for the low CFU-E numbers. After 4 weeks of exposure to all benzene concentrations, greater than 17 days in benzene-free atmosphere are needed for a complete recovery of BFU-E and CFU-E compartment sizes.

Reduction of benzene toxicity by toluene.

BDF1 mice were exposed in inhalation chambers to benzene (900 ppm, 300 ppm) and/or toluene (500 ppm, 250 ppm) 6 hr per day, 5 days per week, for up to 8 weeks. Benzene alone induced a slight anemia after 4 and 8 weeks and a reduction of BFU-E and CFU-E numbers in the marrow. The coexposure to toluene reduced the degree of anemia. These results confirm previous studies where toluene was found to reduce benzene toxicity. This protective effect was most pronounced when DNA damage was studied in peripheral blood cells, bone marrow, and liver using the single cell gel (SCG) assay. With benzene alone, either with 300 or 900 ppm, a significant increase in DNA damage was detected in cells sampled from all three organs. Toluene alone did not induce a significant increase in DNA damage. The coexposure of benzene and toluene reduced the extent of DNA damage to about 50% of benzene alone. This result is considered a clear indication for a protective effect of toluene on the genetic toxicity of benzene.

Post-operative internal hernia through an orifice underneath the right common iliac artery after Dargent's operation.

We report the case of a 39-year-old woman with ileus resulting from a small bowel incarceration underneath the right common iliac artery. The patient had a history of a radical trachelectomy with laparoscopic pelvic lymphadenectomy ("Dargent's operation") for cervical carcinoma. After dissection of the iliac vessels, a small bowel loop could slide underneath the common iliac artery. The hernia was closed by gluing a collagen patch over the right common iliac artery onto the retroperitoneal cavity. To our knowledge, such a case has not previously been reported in the medical literature.

Conversion to mycophenolate mofetil for modulating recurrent hepatitis C in liver transplant recipients.

BACKGROUND: The aim of this study was to analyze the influence of cyclosporine A (CsA) taper in conjunction with mycophenolate mofetil (MMF) therapy on recurrent hepatitis C virus (HCV) in liver transplant patients. PATIENTS AND METHODS: Nineteen liver recipients with serologically and morphologically confirmed recurrent HCV were included in this study. After MMF introduction up to a maximum dose of 2000 mg/day, CsA dose was significantly tapered. In the control group immunosuppression remained unchanged. Allograft function and morphology, viral loads, and renal function were analyzed continuously. RESULTS: MMF treatment was well tolerated without risk of rejection. Allograft fibrosis progressed in 6 patients of the MMF group (66.6%) and none (0%) of the controls at 12-month biopsy (P=0.005). Moreover, aminotransferases and viral loads increased slightly in the MMF-treated patients. Renal function improved significantly (serum creatinine: 239.3+/-90.2 micromol/L vs. 175.8+/-46.0 micromol/L; P=0.008) in the treatment group, while deteriorating (serum creatinine: 156.8+/-44.6 micromol/L vs. 214.8+/-120.1 micromol/L; P=0.06) in the controls. CONCLUSION: MMF introduction allows a safe CsA taper in HCV-positive liver transplant patients and results in significant improvement of renal function. However, there seems to be a risk of marked progression of HCV-induced allograft injury.

[High incidence of lung cancer in persons with chronic professional exposure to pesticides in agriculture (author's transl)]. / Gehäuftes Vorkommen von Bronchialkrebs bei beruflicher Pestizidexposition in der Landwirtschaft

In an epidemiological study in the Neubrandenburg district among 316 long-term exposed pesticide workers the incidence of tumors was investigated. There were 30 cases of tumors, of which 11 were lung cancers. The incidence of lung cancers was in contrast to age-specific population twenty times higher. The average exposure against pesticides amounted to 14.1 +/- 4.7 (6-23) years, the latency period between exposition start and tumor manifestation to 17.9 +/- 6.0 (6-23) years. The exposure occurred mainly to the following agents: herbicides, such as derivatives of phenoxyacetic acid (2,4 D and MCPA); insecticides, such as chlorinated hydrocarbons (DDT, HCH and Toxaphen), organic phosphorus compounds (Parathion) and organic nitro derivatives (DNOC) as well as fungicides, such as copper containing and organic synthetic agents. Between 1950 and 1956 some pesticide workers were also exposed to arsenic containing agents. As the workers were exposed to various chemical compounds simultaneously or alternatively, no carcinogenic effect can be determined by specific individual pesticides. The investigations are discussed in detail on the today knowledge about cancer hazards associated with exposure to pesticides, and respective conclusions are drawn for preventive measures.

[Alternate-day prednisolone therapy in lung sarcoidosis (author's transl)]. / Alternierende Prednisolontherapie bei Lungensarkoidose

Thirty patients with a biopsy-proven sarcoidosis of the lung (state I = 5, state II = 24, state III = 1 patient(s) were subjected to a primary alternate-day prednisolone therapy. After a treatment of 6 months all signs of sarcoidosis of state I and about two thirds of state II disappeared completely. In one third of the cases of state II (mainly broad focal and extensively infiltrative types of sarcoidosis as well as relapses the inflammatory changes in patients could be suppressed, but moderate fibrous residues remained. One case of progressive sarcoidosis of state III proved to be nearly resistant to therapy. Substantial side effects were not observed. Since the alternate-day prednisolone therapy is highly effective and nearly without any risk it is recommended to all patients with sarcoidosi needing therapy.