Tunable viscosity modification with diluted particles: When particles decrease the viscosity of complex fluids

While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations. Extended studies and theories on non-spherical particles find a more complicated behavior, but still a steady increase. Involving platelets in combination with complex fluids displays an even more complex scenario that we analyze experimentally and theoretically as a function of platelet diameter, to find the underlying concepts. Using a broad toolbox of different techniques we were able to decrease the viscosity of crude oils although solid particles were added. This apparent contradiction could lead to a wider range of applications.Comment: 13+7 pages, 6+7 figure

Geometric Phases generated by the non-trivial spatial topology of static vector fields coupled to a neutral spin-endowed particle. Application to 171Yb atoms trapped in a 2D optical lattice

We have constructed the geometric phases emerging from the non-trivial topology of a space-dependent magnetic field, interacting with the spin magnetic moment of a neutral particle. Our basic tool is the local unitary transformation which recasts the magnetic spin interaction under a diagonal form. Rewriting the kinetic term in the "rotated" frame requires the introduction of non-Abelian covariant derivatives, involving the gradients of the Euler angles which define the orientation of the local field. Within the rotated frame, we have built a perturbation scheme,assuming that the longitudinal non-Abelian field component dominates the transverse ones, to be evaluated to second-order. The geometry embedded in the longitudinal gauge vector field and its curl, the geometric magnetic field, is described by the associated Aharonov-Bohm phase. As an illustration, we study the physics of cold 171Yb atoms dressed by two sets of circularly polarized beams, forming square or triangular 2D optical lattices. The geometric field is computed explicitly from the Euler angles. The magnitude of 2nd-order corrections due to transverse fields can be reduced to the percent level by a choice of light intensity which keeps the dressed atom loss rate below 5 s^{-1}. An auxiliary optical lattice confines the atoms within 2D domains where the geometric field is pointing upward.Comment: 12 pages, 4 figures. Comments and one figure added about the effect of the additional scalar potential (sec. V.B). To be published in J. Phys. A:Math. Theo

Ischemia-Reperfusion Injury and Pregnancy Initiate Time-Dependent and Robust Signs of Up-Regulation of Cardiac Progenitor Cells

To explore how cardiac regeneration and cell turnover adapts to disease, different forms of stress were studied for their effects on the cardiac progenitor cell markers c-Kit and Isl1, the early cardiomyocyte marker Nkx2.5, and mast cells. Adult female rats were examined during pregnancy, after myocardial infarction and ischemia-reperfusion injury with/out insulin like growth factor-1(IGF-1) and hepatocyte growth factor (HGF). Different cardiac sub-domains were analyzed at one and two weeks post-intervention, both at the mRNA and protein levels. While pregnancy and myocardial infarction up-regulated Nkx2.5 and c-Kit (adjusted for mast cell activation), ischemia-reperfusion injury induced the strongest up-regulation which occurred globally throughout the entire heart and not just around the site of injury. This response seems to be partly mediated by increased endogenous production of IGF-1 and HGF. Contrary to c-Kit, Isl1 was not up-regulated by pregnancy or myocardial infarction while ischemia-reperfusion injury induced not a global but a focal up-regulation in the outflow tract and also in the peri-ischemic region, correlating with the up-regulation of endogenous IGF-1. The addition of IGF-1 and HGF did boost the endogenous expression of IGF and HGF correlating to focal up-regulation of Isl1. c-Kit expression was not further influenced by the exogenous growth factors. This indicates that there is a spatial mismatch between on one hand c-Kit and Nkx2.5 expression and on the other hand Isl1 expression. In conclusion, ischemia-reperfusion injury was the strongest stimulus with both global and focal cardiomyocyte progenitor cell marker up-regulations, correlating to the endogenous up-regulation of the growth factors IGF-1 and HGF. Also pregnancy induced a general up-regulation of c-Kit and early Nkx2.5+ cardiomyocytes throughout the heart. Utilization of these pathways could provide new strategies for the treatment of cardiac disease

Molecular monitoring of acute graft-versus-host disease after allogenic stem cell transplantation

Acute graft-versus-host disease (GVHD) remains a major barrier to the wider application of allogeneic stem cell transplantation (SCT) for a variety of diseases. GVHD occurs when the transplanted donor Tlymphocytes react to host antigens on antigen-presenting cells and attack host tissues. The donor lymphocytes are introduced into a milieu that promotes their direct attack on target cells, causing tissue damage through perform, granzyme B, and Fas/Fas ligand (FasL) interactions. In addition, the dysregulated production of inflammatory cytokines, such as TNF-alpha, IFN-gamma, IL-1, and others, may cause direct tissue damage. The immunobiology of acute GVHD is complex and the precise mechanisms by which host tissues are damaged remain unclear. Despite progress in understanding the mediators involved in acute GVHD, treatment has remained frustrating; most patients who develop the severe manifestations of GVHD succumb to it or to complications of its treatment. Today, the only available method of diagnosing acute GVHD relies on clinical observations and clinical judgments. Since plenty of other problems can influence the symptoms seen in patients after SCT and further confuse the picture of the patient's disease, diagnosing acute GVHD can be rather difficult. It is well known that predicting the risk of acute GVHD before its clinical manifestation and early administration of additional therapy may result in less incidence of severe GVHD. Hence, new methods to diagnose acute GVHD are desired. Therefore, the major aim of this thesis has been to find new reliable molecular methods to diagnose acute GVHD after allogeneic SCT. The gene expression of T-cell effector molecules, granzym B, perform, FasL, and TNF-alpha, was evaluated as diagnostic markers for acute GVHD after SCT. Peripheral blood samples from patients were analysed by competitive or real-time polymerase chain reaction (PCR). An up-regulation of the gene expression of was seen in association with acute GVHD diagnosis in 23 of 27, 26 of 27, and 24 of 27 patients diagnosed with acute GVHD for granzyme B, perform and FasL, respectively. The gene expression of TNF-alpha did not show the same pattern. Interestingly, we also found that patients with increasing levels during steroid treatment, 2 of 3 in Paper I and 10 of 10 in Paper II, showed persistent or deteriorating acute GVHD. Using VNTR analysis, chimerism patterns were investigated in 34 patients during the early posttransplantation period. The difference in the clearance rate of host T-cells between day 7 and day 10 was compared. In this study, we found that there was a significantly higher risk for patients with complete donor chimerism on day 7, together with patients with an increase of more than 50% in the donor CD4+ T-cell population between day 7 and 10, to develop grades II-IV acute GVHD. Our data indicate that early monitoring of T-cell chimerism after SCT may be of use for early identification of patients at risk of developing moderate to severe acute GVHD after SCT. We hypothesized that the gene expression of chemokine receptors in peripheral blood from patients after SCT would reflect the development of acute GVHD since these molecules are involved in the recruitment of activated T-lymphocytes during acute GVHD. Quantitative real-time PCR was used to assess the gene expression of the chemokine receptors CCR5, CXCR3, CCR1, and CCR2. In this study we found that increasing levels of these receptors were associated with acute GVHD. We found increasing levels in connection to acute GVHD diagnosis of all four markers in 35, 33, 35, and 35 of 46 occasions of acute GVHD for CCR5, CXCR3, CCR1, and CCR2, respectively. Another important finding was that the gene expression levels increased before acute GVHD was diagnosed clinically with the median number of days before diagnosis ranging from 3 to 5 days. In conclusion, although the pathophysiology of acute GVHD still remains complex, this study shows that different molecular markers involved in this complicated disorder may be used to diagnose and predict acute GVHD and to monitor steroid treatment. This may prevent life-threatening complications and improve the outcome for patients after allogeneic SCT

Flow of Microemulsions Adjacent to Planar Surfaces

Microemulsions consist of water, oil and surfactant. Although thermodynamically stable, domains of pure water and oil are formed on nanometer length scales and a surfactant film in between that are ideally observable by small angle scattering experiments. The bicontinuous microemulsion displays a sponge structure that forms when equal volumes of water and oil are mixed. Being exposed to hydrophilic planar surfaces, a lamellar order is found in the vicinity to the solid-liquid interface. The typical depth of the lamellae is 40 to 60nm, i.e. 4 to 6 perfect domains [1,2], before the perforations describe the decay to the bicontinuous phase. The membrane modes observed by neutron spin echo spectroscopy under grazing incidence are faster at the interface than in bulk [3]. This is an evidence for the lubrication effect, a facilitated flow of the lamellae along the interface. Employing clay platelets, the same effect could be observed in a bulk sample [4]. Furthermore, at smaller platelet diameters, the favorable modes of the lamellae were cut, and the overall dynamics slowed down similar to the bulk. Thus, the perfection of modes at the interface is connected to the platelet diameter. At rather high flow rates, the perforated transition region was reduced in size, while the perfect lamellae were persistent [2]. In macroscopic rheology experiments (Fig.1 left), the microemulsion with rather large clay platelets showed evidence for the lubrication effect on macroscopic scales, while at lower clay dimensions the viscosity was extraordinarily high [5] (Fig.1 right). Motivated by this effect, the rheology of crude oils with large clay platelets showed decreased viscosities at low temperatures (below 0°C). The dynamic asymmetry of the aromatic and aliphatic portions and the lamellar alignment of the domains may explain these findings

Nicotinamide riboside is uniquely and orally bioavailable in mice and humans

Nicotinamide riboside (NR) is in wide use as an NAD(+) precursor vitamin. Here we determine the time and dose-dependent effects of NR on blood NAD(+) metabolism in humans. We report that human blood NAD(+) can rise as much as 2.7-fold with a single oral dose of NR in a pilot study of one individual, and that oral NR elevates mouse hepatic NAD(+) with distinct and superior pharmacokinetics to those of nicotinic acid and nicotinamide. We further show that single doses of 100, 300 and 1,000 mg of NR produce dose-dependent increases in the blood NAD(+) metabolome in the first clinical trial of NR pharmacokinetics in humans. We also report that nicotinic acid adenine dinucleotide (NAAD), which was not thought to be en route for the conversion of NR to NAD(+), is formed from NR and discover that the rise in NAAD is a highly sensitive biomarker of effective NAD(+) repletion

KWS-1 high-resolution small-angle neutron scattering instrument at JCNS: current state

The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Jülich Centre for Neutron Science (JCNS) at the research reactor FRM II of the Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. The KWS-1 instrument was updated, from its active collimation apertures to the detector cabling. Most of the parts of the instrument were installed for the first time, including a broadband polarizer, a large-cross-section radio-frequency spin flipper, a chopper and neutron lenses. A custom-designed hexapod in the sample position allows heavy loads and precise sample positioning in the beam for conventional SANS experiments as well as for grazing-incidence SANS under applied magnetic field. With the foreseen in situ polarization analysis the main scientific topic of the instrument tends towards magnetism. The performance of the polarizer and flipper was checked with a polarized 3He cell at the sample position. The results of these checks and a comparison of test measurements on a ferrofluid in a magnetic field with polarized and nonpolarized neutrons are presented

Immunohistochemical analysis of Nkx2.5, c-Kit and Isl1 cardiac progenitors.

<p><b>Section A:</b> The distribution of Nkx2.5+ cells in the myocardium of the different groups together with semi-quantitative analysis. Figures (a-f) represent: 9.5 weeks human fetal heart as a positive control (a), followed by left ventricular regions from the; control (b), pregnancy (c), myocardial infarction (d), ischemia-reperfusion (e) and ischemia-reperfusion+growth factors (f) groups, respectively. The delineated areas in figure b-f represent a higher magnification of that region. Bars in panel (a-f) = 100 µm. Figure (g) demonstrates the relative number of Nkx2.5+ cells in relation to the total number of cells in the different groups. Data is presented as mean± SD. *<i>P</i><0.05. <b>Section B</b>: Representative stainings of c-Kit+cells in: adult rat kidney as positive control (a), followed by the left ventricular regions from the ischemia-reperfusion+growth factors (b, d) and myocardial infarction groups (e). The delineated area in figure (b) is magnified (100 x) in figure (c). In figures (b-e), red arrows indicate c-Kit+ cells. Bars in figures (a, b) = 100 µm and in figures (c-e) = 50 µm. Figure (f) demonstrates the percentage of c-Kit+cells in relation to the total number of cells in the different groups. Data is presented as mean ± SD. <i>*P<0.05 and **P<0.001. </i><b>Section C</b>. Representative stainings of Isl1+ cells in whole heart cytospins from (c) pregnancy, (d) myocardial infarction, (e) ischemia-reperfusion and (f) ischemia-reperfusion+growth factors groups. Figures (a) and (b) represent the positive controls; whole rat embryo ED13 and insulin cell line-1E respectively. Delineated areas in figure c, d, e and f represent a higher magnification of that region. Bars in figures (a–f) = 100µm. In figure; ED: embryonic day; MI: myocardial infarction; IR: ischemia-reperfusion; IR+GF: ischemia-reperfusion+growth factors.</p