Spectral Dimension and Random Walks on the Two Dimensional Uniform Spanning Tree

We study the simple random walk on the uniform spanning tree on \mathbb Z²{\mathbb {Z}^2} . We obtain estimates for the transition probabilities of the random walk, the distance of the walk from its starting point after n steps, and exit times of both Euclidean balls and balls in the intrinsic graph metric. In particular, we prove that the spectral dimension of the uniform spanning tree on \mathbb Z²{\mathbb {Z}^2} is 16/13 almost surely.     

The use of exploratory experimental designs combined with thermal numerical modelling to obtain a predictive tool for hybrid laser/MIG welding and coating processes

While hybrid laser welding and coating processes involve a large number of physical phenomena, it is currently impossible to predict, for a given set of influencing factors, the shape of the molten zone and the history of temperature fields inside the parts. This remains true for complex processes, such as the hybrid laser/MIG welding process, which consists in combining a laser beam with a MIG torch. The gains obtained result essentially from the synergy of the associated processes: the stability of the process, the quality of the seam realized, and the productivity are increased. This article shows how, by means of a reduced number of experiments (8), it is possible to predict the shape of the molten zone and the temperature field inside parts, for a given window of influencing factors. This method consists in combining the method of exploratory experimental designs with a numerical modelling of the thermal phenomena that occurs during the process, by using the ‘heat equivalent source” approach [1], [2], [3], [4]. Two validations of this method have been carried out: the first for a set of parameters inside the experimental design, and the other for a set of parameters that lies outside the experimental design, but inside the domain investigated.     

Studies on Curcumin and Curcuminoids. XXXIX. Photophysical Properties of Bisdemethoxycurcumin

The steady-state absorption and fluorescence, as well as the time-resolved fluorescence properties of bisdemethoxycurcumin dissolved in several solvents differing in polarity and H-bonding capability were measured. The photodegradation quantum yield of the compound in acetonitrile and methanol was determined. The bisdemethoxycurcumin decay mechanisms from the S ₁ state were discussed and compared with those of curcumin. The differences in S ₁ dynamics observed between bisdemethoxy-curcumin and curcumin could be ascribed to a difference in H-bond acceptor/donor properties of the phenolic OH and a difference in strength of the intramolecular H-bond in the keto-enol moiety within the two molecules.     

Synthesis and Reactivity of some Aromatic Sulfides Substituted by an Ortho-Phosphonyl Group

Abstract

As phosphorus-based members of the biologically relevant thiosalicylic acid, monoesters of ortho-sulfinylated phenylphosphonic acids such as 3 and 4 (series a, R¹=Me; b, R²2-C₆H₄C0₂H) are of special interest. They might act both as potential sources of new anionic bidentate ligands for the synthesis of cisplatin analogues^[1] and as suitable precursors of phosphorus-containing endocyclic sulfoximides and hypervalent organo-sulfur species. We have therefore undertaken the synthesis of these compounds. The starting phenylphosphonic acid diisopropylesters 1 were formed by using a LDA-induced thiophosphate-mercaptophosphonate rearrangement^[2] described earlier and converted into their dimethyl counterpans 2 by means of a trans-silylation procedure followed by alkylation. We have now performed the selective half-hydrolysis of phosphonic acid diesters 1.2 and sulfoxidation of the resulting monoesters.     

Molecular modeling of butyrylcholinesterase inhibition by cresyl saligenin phosphate

Presumably, aerotoxic syndrome is caused by the impact of tricresyl phosphate (TCP), a lubricating oil additive for aircraft engines, on the human body. The most toxic tri-ortho-isomer of this compound is metabolized in the body to give cresyl saligenin phosphate (CSP), which inhibits butyrylcholinesterase (BChE) giving phosphoserine. In this case, BChE acts as a stoichiometric bioscavenger irreversibly binding CSP and as a biomarker of exposure to low doses of TCP. The mechanism of CSP interaction with BChE at the initial stage of formation of the enzyme—inhibitor complex was studied by molecular modeling techniques. The results indicate that BChE interaction with the (R)-enantiomer of CSP in the most stable envelope conformation of the saligenin ring is most preferable. Comparison of the results obtained using different computation methods demonstrated that the best agreement with experimental data can be achieved by combining standard molecular docking methods with quantum mechanics methods for more accurate structure preparation.     

Modified peptide monolayer binding His-tagged biomolecules for small ligand screening with SPR biosensors

A peptide self-assembled monolayer (SAM) was designed to bind His-tagged biomolecules for surface plasmon resonance (SPR) bioanalysis, which was applied for the determination of K(d) for small ligand screening against CD36. Nonspecific adsorption could be minimized using penta- and hexa-peptide monolayers. In particular, monolayers consisting of 3-mercaptopropionyl-leucinyl-histidinyl-aspartyl-leucinyl-histidinyl-aspartic acid (3-Mpa-LHDLHD) exhibited little (12 ng cm(-2)) nonspecific adsorption in crude serum. Modification of this peptide monolayer with Nα,Nα-bis(carboxymethyl)-L-lysine gave a surface competent for binding His-tagged proteins, as demonstrated using enzyme (human dihydrofolate reductase), protein/antibody and receptor (CD36) examples. Immobilization featured chelation of copper and the His-tagged protein by the peptide monolayer, which could be recycled by removing the copper using imidazole washes prior to reuse.     

Silica nanoparticles containing a rhodamine dye and multiple gold nanorods

Silica shells are grown around colloidally synthesized gold nanorods (AuNRs) to form core–shell particles (AuNR@SiO₂) of variable occupancy, defined as the number of AuNRs per silica particle. Multiple AuNR occupancy within the silica shell, confirmed with high-resolution electron microscopy, is reflected in a redshift of the longitudinal plasmon mode of the nanorods due to multipolar coupling between AuNRs of a favored end–end orientation. In addition to the plasmon resonance that dominates their absorbance spectra, FL-AuNR@SiO₂, core–shell particles incorporating a lipid probe (rhodamine-DOPE), can be monitored by their fluorescence and Raman signals. Optical and scanning electron microscopy (SEM) images are compared directly, enabling the correlation of spectroscopic characteristics with particle morphology. Raman and SEM images show that the most intense Raman signals come from aggregates of AuNRs trapped within the silica matrix. Biexponential fits to fluorescence decays indicate that competing mechanisms of quenching and fluorescence enhancement contribute to a reduced fluorescence lifetime of rhodamine-DOPE located near the AuNRs.     

Immunization with genetically attenuated P52-deficient Plasmodium berghei sporozoites induces a long-lasting effector memory CD8+ T cell response in the liver

Background

The induction of sterile immunity and long lasting protection against malaria has been effectively achieved by immunization with sporozoites attenuated by gamma-irradiation or through deletion of genes. For mice immunized with radiation attenuated sporozoites (RAS) it has been shown that intrahepatic effector memory CD8⁺ T cells are critical for protection. Recent studies have shown that immunization with genetically attenuated parasites (GAP) in mice is also conferred by liver effector memory CD8⁺ T cells.

Findings

In this study we analysed effector memory cell responses after immunization of GAP that lack the P52 protein. We demonstrate that immunization with p52 ^-GAP sporozoites also results in a strong increase of effector memory CD8⁺ T cells, even 6 months after immunization, whereas no specific CD4⁺ effector T cells response could be detected. In addition, we show that the increase of effector memory CD8⁺ T cells is specific for the liver and not for the spleen or lymph nodes.

Conclusions

These results indicate that immunization of mice with P. berghei p52 ^-GAP results in immune responses that are comparable to those induced by RAS or GAP lacking expression of UIS3 or UIS4, with an important role implicated for intrahepatic effector memory CD8⁺ T cells. The knowledge of the mediators of protective immunity after immunization with different GAP is important for the further development of vaccines consisting of genetically attenuated sporozoites.