Acylsulfonamide safety-catch linker : promise and limitations for solid-phase oligosaccharide synthesis

Safety-catch linkers are useful for solid-phase oligosaccharide synthesis as they are orthogonal to many common protective groups. A new acylsulfonamide safety-catch linker was designed, synthesized and employed during glycosylations using an automated carbohydrate synthesizer. The analysis of the cleavage products revealed shortcomings for oligosaccharide synthesis

Leaf Pubescence: The Significance of Lower Surface Hairs for the Spectral Properties of the Upper Surface

The fraction of the global radiation incident on the upper surface of leaves of Tussilago farfara L. which is reflected, varies according to the presence or absence of hairs on the lower surface. Calculations of the radiation fluxes at 550 and 1000 nm wavelengths prove that these differences arise from a partial reflection of the radiation emerging from the lower epidermis by the hair cove

Gradient-flowed thermal correlators: how much flow is too much?

Gradient flow has been proposed in the lattice community as a tool to reduce the sensitivity of operator correlation functions to noisy UV fluctuations. We test perturbatively under what conditions doing so may contaminate the results. To do so, we compute gradient-flowed electric field two-point correlators and stress tensor one- and two-point correlators at finite temperature in QCD. Gradient flow has almost no influence on the value of correlators until a (temperature- and separation-dependent) level of flow is reached, after which the correlator is rapidly compromised. We provide a prescription for how much flow is "safe."Comment: 15 pages because of 7 figure

Six-body Light-Front Tamm-Dancoff approximation and wave functions for the massive Schwinger model

The spectrum of the massive Schwinger model in the strong coupling region is obtained by using the light-front Tamm-Dancoff (LFTD) approximation up to including six-body states. We numerically confirm that the two-meson bound state has a negligibly small six-body component. Emphasis is on the usefulness of the information about states (wave functions). It is used for identifying the three-meson bound state among the states below the three-meson threshold. We also show that the two-meson bound state is well described by the wave function of the relative motion.Comment: 19 pages, RevTeX, 7 figures are available upon request; Minor errors have been corrected; Final version to appear in Phys.Rev.

Sonoluminescing air bubbles rectify argon

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus it is the partial argon (or any other inert gas) pressure which is relevant for stability. The theory provides quantitative explanations for many aspects of SBSL.Comment: 4 page

Transpiration and water uptake of Senecio medley-woodii and Aloe jucunda under changing environmental conditions: measurements with a potometric water-budget-meter

Transpiration, water uptake by the roots and CO2 exchange of two leaf succulents, Senecio medleywoodii (Asteraceae) and Aloe jucunda (Asphodeliaceae), were monitored simultaneously and continuously with a gas exchange cuvette combined with an apparatus to quantify water uptake (= waterbudget- meter). Measurements, which are primarily valid for plants with a sufficient water supply, were made with the same plant for up to 29 consecutive days. Ambient air temperature varied between 17 and 35 °C with a constant dewpoint temperature of 13°C of the ambient air and a 12 h photoperiod at 400-500µmol m−2s−1 photon irradiance. The net water flux (Jw(net)=water uptake-transpiration) and the water balance (Jw(net) integrated for a timespan) were calculated. Various tests were made to determine the accuracy of the measurements made with this rather complex equipment. In most cases the errors for transpiration and uptake rates were much lower than 8% determined under the conditions of drastically (about 10 K per 30 min) increased or decreased ambient air temperatures. The experimental set-up proved to be a most valuable tool to determine and analyse interactions between transpiration and water uptake, changes in plant water status and the buffering of negative Jwnet). Increasing the temperature of ambient air resulted, for both species investigated, in a quick and considerably enhanced transpiration, but there was only a minor impact on water uptake. Water loss exceeding uptake was buffered by internal water reserves which were refilled within about 1 d after the plant was relieved of heat and drought stress caused by a period of high ambient air temperatures and high water vapour saturation deficits of the air. Repeated simulation of such stress periods showed that the absolute values of transpiration and the water uptake for 24 h can vary, but the diurnal course of the values showed the same pattern if the environmental conditions were identical. Such standardized diurnal transpiration and water uptake curves could be very useful for the validation of mathematical models used to describe plant water relation

Leaf Temperatures in a Gas Exchange Chamber and in the Open Air

Leaf temperatures in a Koch fully climatized gas-exchange chamber as designed by Siemens and in a similarly equipped open-air reference were measured with horizontally and vertically inserted thermocouples on Nerium oleander L. On a sunny day with only little air movement and an average air temperature of 20.4 °C, leaf over-temperatures in the gas-exchange chamber were lower on average by 2.2 K. The extent of reduction of over-temperature in the chamber is determined by the reduced global radiation in the chamber and the differences of wind velocities in chamber and reference. Differences in the ventilation intensity in the chamber have no demonstrable influence on the leaf over-temperatures. The over-temperatures of the reference leaves, on the other hand, depend to a large degree on air velocity. The changed radiation and air flow conditions in the chamber as compared with open-air conditions have consequences for the physiological reactions of the enclosed plant and must be taken into account when comparing results from gas-exchange measurements with open-air conditions. For further improvements of gas-exchange measurement equipment, air flow conditions and radiation quantity and quality might be starting point

Dynamics of the Light-Cone Zero Modes: Theta Vacuum of the Massive Schwinger Model

The massive Schwinger model is quantized on the light cone with great care on the bosonic zero modes by putting the system in a finite (light-cone) spatial box. The zero mode of $A_{-}$ survives Dirac's procedure for the constrained system as a dynamical degree of freedom. After regularization and quantization, we show that the physical space condition is consistently imposed and relates the fermion Fock states to the zero mode of the gauge field. The vacuum is obtained by solving a Schr\"odinger equation in a periodic potential, so that the theta is understood as the Bloch momentum. We also construct a one-meson state in the fermion-antifermion sector and obtained the Schr\"odinger equation for it.Comment: 23 pages, RevTex, no figure

Pathfinder cells provide a novel therapeutic intervention for acute kidney injury

Pathfinder cells (PCs) are a novel class of adult-derived cells that facilitate functional repair of host tissue. We used rat PCs to demonstrate that they enable the functional mitigation of ischemia reperfusion (I/R) injury in a mouse model of renal damage. Female C57BL/6 mice were subjected to 30 min of renal ischemia and treated with intravenous (i.v.) injection of saline (control) or male rat pancreas-derived PCs in blinded experimentation. Kidney function was assessed 14 days after treatment by measuring serum creatinine (SC) levels. Kidney tissue was assessed by immunohistochemistry (IHC) for markers of cellular damage, proliferation, and senescence (TUNEL, Ki67, p16ink4a, p21). Fluorescence in situ hybridization (FISH) was performed to determine the presence of any rat (i.e., pathfinder) cells in the mouse tissue. PC-treated animals demonstrated superior renal function at day 14 post-I/R, in comparison to saline-treated controls, as measured by SC levels (0.13 mg/dL vs. 0.23 mg/dL, p<0.001). PC-treated kidney tissue expressed significantly lower levels of p16ink4a in comparison to the control group (p=0.009). FISH analysis demonstrated that the overwhelming majority of repaired kidney tissue was mouse in origin. Rat PCs were only detected at a frequency of 0.02%. These data confirm that PCs have the ability to mitigate functional damage to kidney tissue following I/R injury. Kidneys of PC-treated animals showed evidence of improved function and reduced expression of damage markers. The PCs appear to act in a paracrine fashion, stimulating the host tissue to recover functionally, rather than by differentiating into renal cells. This study demonstrates that pancreatic-derived PCs from the adult rat can enable functional repair of renal damage in mice. It validates the use of PCs to regenerate damaged tissues and also offers a novel therapeutic intervention for repair of solid organ damage in situ