New enumerative results on two-dimensional directed animals

We list several open problems concerning the enumeration of directed animals on two-dimensional lattices. We show that most of these problems are special cases of two central problems: calculating the position generating function and the perimeter and area generating function for square lattice animals.

We propose a possible direction for solving these two problems: we extend Dhar's correspondence between hard particle gas models and enumeration of animals according to the area, and show that each of the main two generating functions is, essentially, the density of a one-dimensional gas model given by the stationary distribution of a probabilistic transition.

We are able to compute the density of certain stationary distributions. We thus obtain new bivariate generating functions for directed animals on the square and triangular lattices. We derive from these results the generating functions for animals on the decorated square and triangular lattices, as well as the average number of loops in directed animals.     

Investigation of ion-selective electrodes with neutral ionophores and ionic sites by EIS. II. Application to K detection

The impedance of an ion-selective electrode (ISE) to potassium with valinomycin as the ionophore and KBΦ₄ as the ionic sites was measured. The membrane was made of PVC with DNP as a plasticizer. The influence of the content of the plasticizer and the membrane thickness was investigated. The concentrations of the ionophore and the ionic sites were changed to modify the response on the ISE. Finally, the selectivity was tested in terms of impedance. All impedance experiments were correlated to the potentiometric curves plotted under the same experimental conditions. The measured impedances were compared to the model proposed in the previous paper (paper I). A good agreement was found.     

Photothermal deflection microscopy for imaging sub-micronic defects in optical materials

Photothermal deflection is widely used to study defects in optical coatings and role of these defects in laser damage. Because defects responsible for laser damage are assumed to be nanometer-sized and lowly absorbing, both high spatial resolution and high sensitivity are required to detect them. In this work we theoretically and experimentally explore the capability of collinear photothermal deflection to give micronic resolution by reduction of the pump beam diameter. Thanks to a model describing temperature distribution and photothermal deflection, we have studied the effects of pump beam focusing on photothermal deflection. Then, we have developed a high resolution, high sensitivity microscope based on the photothermal deflection of a transmitted probe beam. The setup is characterized and the theoretical predictions are checked. We present a test of lateral spatial resolution obtained on specially prepared absorbing resolution targets and show that a lateral spatial resolution of 1 μm is reached on non-isolated defects. In case of single defects, we expect that 10 nm sized defects could be detected.     

Novel π2s+π2a Electrocyclization of Triethylenic‐Malonic Acids Exemplified for a One‐Pot Synthesis of New γ‐Dilactones cis‐Fused with a Cyclopentene

A new, easy and rapid synthesis of γ‐dilactones is cis‐fused with a cyclopentenic ring via cyclization of 7‐chlorotriethylenic‐malonic acids. The key step implicates an intramolecular cyclization to a cyclopentenyl cation, according to an electrocyclic π_2s + π_2a conrotatory process. This cyclopentenyl cation led to unstable γ‐lactones intermediates that are rearrange to more stable isomers. δ‐lactones (6Z and 6E‐(3‐chlorobut‐2‐en‐2‐yl)‐5‐methyl‐3,6‐dihydro‐2H‐pyran‐2‐one) were obtained as secondary products. Mechanistic pathways were considered. The structures of the newly synthesized compounds were established by elemental and spectral data.     

Mannose‐6‐Phosphate Receptor: A Target for Theranostics of Prostate Cancer

The development of personalized and non‐invasive cancer therapies based on new targets combined with nanodevices is a major challenge in nanomedicine. In this work, the over‐expression of a membrane lectin, the cation‐independent mannose 6‐phosphate receptor (M6PR), was specifically demonstrated in prostate cancer cell lines and tissues. To efficiently target this lectin a mannose‐6‐phosphate analogue was synthesized in six steps and grafted onto the surface of functionalized mesoporous silica nanoparticles (MSNs). These MSNs were used for in vitro and ex vivo photodynamic therapy to treat prostate cancer cell lines and primary cell cultures prepared from patient biopsies. The results demonstrated the efficiency of M6PR targeting for prostate cancer theranostic.     

Polar Diketopyrrolopyrrole‐Imidazolium Salts as Selective Probes for Staining Mitochondria in Two‐Photon Fluorescence Microscopy

Three rationally designed polar derivatives of diketopyrrolopyrrole consisting of 1,3‐dimethylimidazolium cationic units and benzene, thiophene, or furan rings as π spacers were synthesized and thoroughly studied. The obtained salts are soluble in polar organic solvents and show satisfactory solubility in water, which makes them suitable for the applications in bioimaging. Photophysical measurements revealed that the obtained derivatives are characterized by strong absorption and good fluorescence quantum yields. The corresponding two‐photon properties were also examined and showed that the synthesized salts exhibit large two‐photon absorption cross‐sections reaching 4000 GM (GM=Goeppert‐Mayer unit, 1 GM=10^?50 cm⁴ s photon^?1) and very high two‐photon brightness values exceeding 2000 GM. It was demonstrated that these salts can be safely applied in two‐photon fluorescence microscopy for selective staining of mitochondria in living cells.     

New cyclen-cored dendrimers functionalized with pyrene: Synthesis characterization,optical and photophysical properties

New cyclen (1,4,7,10-teraazacyclododecane) cored dendrimers up to the second generation, functionalized with 4, 8 and 16 pyrene units, respectively, were synthesized following a convergent procedure. All new compounds were characterized by NMR spectroscopies and ESI or MALDI TOF mass spectrometry. The optical and photophysical properties of the new dendrimers were studied in THF solution. Absorption spectra showed the typical absorption bands of pyrene moieties. In the fluorescence spectra, monomer as well as excimer emission were observed for all compounds. An increased proportion of excimer emission was observed in the dendrimer of the highest generation.     

Probing the Structural Dynamics of a Bacterial Chaperone in Its Native Environment by Nitroxide-Based EPR Spectroscopy

One of the greatest current challenges in structural biology is to study protein dynamics over a wide range of timescales in complex environments, such as the cell. Among magnetic resonances suitable for this approach, electron paramagnetic resonance spectroscopy coupled to site-directed spin labeling (SDSL-EPR) has emerged as a promising tool to study protein local dynamics and conformational ensembles. In this work, we exploit the sensitivity of nitroxide labels to report protein local dynamics at room temperature. We demonstrate that such studies can be performed while preserving both the integrity of the cells and the activity of the protein under investigation. Using this approach, we studied the structural dynamics of the chaperone NarJ in its natural host, Escherichia coli. We established that spin-labeled NarJ is active inside the cell. We showed that the cellular medium affects NarJ structural dynamics in a site-specific way, while the structural flexibility of the protein is maintained. Finally, we present and discuss data on the time-resolved dynamics of NarJ in cellular context.     

Comparison of open digestion methods and selection of internal standards for the determination of Rh,Pd and Pt in plant samples by ICP-MS

An analytical procedure for the reliable determination of Pd, Pt and Rh in plant samples by inductively coupled plasma-mass spectrometry (ICP-MS) was developed. An ultrasonic nebulizer (USN) was used for sample introduction to improve sensitivity. Under various synthetic plant sample matrix compositions, it was established experimentally that moderate amounts (0.2–2%) of dissolved solids decreased the analyte signals significantly. Internal standardisation with In (for Pd and Rh) and Ir (for Pt) proved to be essential for obtaining correct results. Five open digestion approaches, used for converting solid plant samples to aqueous solution, were also tested for the purpose, namely dry-ashing, dry-ashing followed by HF attack, wet digestion with H₂O₂–HNO₃, wet digestion followed by HF attack and aqua regia digestion. Recovery tests in two spiked plant materials showed that only wet digestions must be used. With these ways, all PGEs could be reliably quantified by USN-ICP-MS without applying a separation or preconcentration step with a good precision (below 10% RSD). The aqua regia procedure was applied to the determination of PGEs in various plant matrices collected along a highway. Results showed that mosses were probably the best choice of samples to monitor the bioaccumulation of PGEs in time.