XPS and resistive studies on thin films of a copper(II)‐based coordination polymer deposited on functionalized interdigital electrodes

A symmetrical 2‐thiopyrimidine based molecule with an expanded π‐electron system is synthesized and used to form a self‐assembled monolayer (SAM) on gold surfaces. Utilizing chemical vapor deposition a monolayer of (3‐mercaptopropyl)triethoxysilane is formed on silicon dioxide substrates. Both of these SAM coated substrates are characterized by X‐ray photoelectron spectroscopy and the growth of a coordination polymer built up from 5,5′‐(ethyne‐1,2‐diyl)bis(2‐hydroxyacetophenone) and copper(II) on dual SAM coated transducers is studied. After the deposition procedure on interdigital electrodes the electrical properties of the polymer are investigated performing resistive measurements. A significant change of the resistance, which depends on the surrounding atmosphere, proves the sensing behavior of the synthesized coordination polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 335–344     

Direct Introduction of an Alkylsulfonamido Group on C-sites of Isomeric Dicarba-closo-dodecaboranes: The Influence of Stereochemistry on Inhibitory Activity against the Cancer-Associated Carbonic Anhydrase IX Isoenzyme

Carbonic anhydrase IX (CA IX), a tumor-associated metalloenzyme, represents a validated target for cancer therapy and diagnostics. Herein, we report the inhibition properties of isomeric families of sulfonamidopropyl-dicarba-closo-dodecaboranes group(s) prepared using a new direct five-step synthesis from the corresponding parent cages. The protocol offers a reliable solution for synthesis of singly and doubly substituted dicarba-closo-dodecaboranes with a different geometric position of carbon atoms. The closo-compounds from the ortho- and meta-series were then degraded to corresponding 11-vertex dicarba-nido-undecaborate(1−) anions. All compounds show in vitro enzymatic activity against CA IX in the low nanomolar or subnanomolar range. This is accompanied by clear isomer dependence of the inhibition constant (K_i) and selectivity towards CA IX. Decreasing trends in K_i and selectivity index (S_I) values are observed with increasing separation of the cage carbon atoms. Interactions of compounds with the active sites of CA IX were explored with X-ray crystallography, and eight high-resolution crystal structures uncovered the structural basis of inhibition potency and selectivity.     

Evidence for Multiple Binding Modes in the Initial Contact Between SARS-CoV-2 Spike S1 Protein and Cell Surface Glycans**

Infection of host cells by SARS-CoV-2 begins with recognition by the virus S (spike) protein of cell surface heparan sulfate (HS), tethering the virus to the extracellular matrix environment, and causing the subunit S1-RBD to undergo a conformational change into the ‘open’ conformation. These two events promote the binding of S1-RBD to the angiotensin converting enzyme 2 (ACE2) receptor, a preliminary step toward viral-cell membrane fusion. Combining ligand-based NMR spectroscopy with molecular dynamics, oligosaccharide analogues were used to explore the interactions between S1-RBD of SARS CoV-2 and HS, revealing several low-specificity binding modes and previously unidentified potential sites for the binding of extended HS polysaccharide chains. The evidence for multiple binding modes also suggest that highly specific inhibitors will not be optimal against protein S but, rather, diverse HS-based structures, characterized by high affinity and including multi-valent compounds, may be required.     

Distance-regular Cayley graphs with least eigenvalue $$$$

We classify the distance-regular Cayley graphs with least eigenvalue \(-2\) and diameter at most three. Besides sporadic examples, these comprise of the lattice graphs, certain triangular graphs, and line graphs of incidence graphs of certain projective planes. In addition, we classify the possible connection sets for the lattice graphs and obtain some results on the structure of distance-regular Cayley line graphs of incidence graphs of generalized polygons.     

An efficient anti-aliasing spectral continuous window shifting technique for PIV

A new sub-pixel correlation peak locating algorithm for PIV analysis is introduced. The method is theoretically consistent with the method of continuously shifting interrogation sub-windows by fractional displacements, which has proven to be an effective way to reduce the bias error associated with integer pixel aliasing, or peak-locking. However the proposed algorithm performs continuous window shifting in the spatial frequency domain using the shift property of the Fourier transform, thus it is equivalent to interpolating the original digital image with the Fourier transform reconstruction. Synthetic and real PIV images are used to test the new algorithms performance relative to that of traditional (non-iterative) peak-finding methods and other peak-locking reduction algorithms, such as the continuous window shifting technique. The resultant bias error of the proposed algorithm is smaller (by an order of magnitude in some cases), and importantly, the periodic nature of the bias error, the characteristic signature of peak-locking, is eliminated as long as the discrete particle images have been sampled at a rate greater than the Nyquist sampling frequency. Moreover, this new algorithm is shown to be computationally efficient and it converges faster than the competing algorithms.     

Water confined in two-dimensions: Fundamentals and applications

The behavior of water in close proximity to other materials under ambient conditions is of great significance due to its importance in a broad range of daily applications and scientific research. The structure and dynamics of water at an interface or in a nanopore are often significantly different from those of its bulk counterpart. Until recently, experimental access to these interfacial water structures was difficult to realize. The advent of two-dimensional materials, especially graphene, and the availability of various scanning probe microscopies were instrumental to visualize, characterize and provide fundamental knowledge of confined water. This review article summarizes the recent experimental and theoretical progress in a better understanding of water confined between layered Van der Waals materials. These results reveal that the structure and stability of the hydrogen bonded networks are determined by the elegant balance between water-surface and water-water interactions. The water-surface interactions often lead to structures that differ significantly from the conventional bilayer model of natural ice. Here, we review the current knowledge of water adsorption in different environments and intercalation within various confinements. In addition, we extend this review to cover the influence of interfacial water on the two-dimensional material cover and summarize the use of these systems in potential novel applications. Finally, we discuss emerged issues and identify some flaws in the present understanding.