A mild,rapid and convenient esterification of half esters of malonic acid

A new method for the esterification of half esters of malonic acid with chloroformates is described. The reaction proceeds $\text{via}$ the mixed anhydride followed by spontaneous decarboxylation.     

Experimental and Theoretical Study of the Reactivity of Gold Nanoparticles Towards Benzimidazole‐2‐ylidene Ligands

The reactivity of benzimidazol‐2‐ylidenes with respect to gold nanoparticles (AuNPs) has been investigated using a combined experimental and computational approach. First, the grafting of benzimidazol‐2‐ylidenes bearing benzyl groups on the nitrogen atoms is described, and comparisons are made with structurally similar N‐heterocyclic carbenes (NHCs) bearing other N‐groups. Similar reactivity was observed for all NHCs, with 1) the erosion of the AuNPs under the effect of the NHC and 2) the formation of bis(NHC) gold complexes. DFT calculations were performed to investigate the modes of grafting of such ligands, to determine adsorption energies, and to rationalize the spectroscopic data. Two types of computational models were developed to describe the grafting onto large or small AuNPs, with either periodic or cluster‐type DFT calculations. Calculations of NMR parameters were performed on some of these models, and discussed in light of the experimental data.     

Complexation and Sensing Behavior of Dansyl-appended Cyclodextrins and Cyclodextrin Dimers with Bile Salts

The dansyl-modified cyclodextrin derivatives 2 and 3 form complexes with the steroidal bile salts. The selectivity of the monomeric derivative 3 is similar to that of native g -cyclodextrin. All binding constants with 3 are lowered compared to g -cyclodextrin because of the competition for the cavity between the steroids and the dansyl moiety. Cholate ( 4a ) and deoxycholate ( 4b ) form weak complexes, the other bile salts ( 4c - e ) are complexed far more strongly. The difference is attributed to the absence of a 12-hydroxy group in the latter steroids. Data for dimer 2 reveal strongly enhanced binding of 4a and 4b and only slightly stronger complexes with the other steroids. Due to the low binding affinity of 3 for 4a and 4b , this receptor could not be used for their detection by fluorescence spectroscopy. Steroids 4c - e showed a decrease in fluorescence intensity. The detection of all steroids 4a - e was possible using 2 . The fluorescence intensity of the dimer increased or decreased, depending on which steroid was added.     

Statistical analysis of data from accelerated ageing tests of PES UF membranes

In this research, membrane life-time was evaluated by means of accelerated ageing experiments. A pressure pulse unit was used to perform the ageing experiments in an accelerated way. An experimental design has been set up and four ageing factors were varied at two levels. The four ageing factors studied were: fouling status of the membrane, cleaning agent concentration, magnitude of the back pulse and number of applied back pulses. The integrity of the membrane modules was evaluated by means of permeability testing, pressure decay tests and bubble tests. Also tensile tests were performed to investigate the mechanical properties of the membrane modules. The collected data was used for an analysis of variance to determine which ageing factors and which combination of ageing factors influence membrane life time. The analysis showed that the fouling status in combination with the number of applied pressure pulses were significant ageing factors. Additional tensile tests confirmed these results.     

Optical fiber based radial polarizer

In this paper we present a new type of optical fiber aiming to radially polarize the electrical field. This special device is composed of a tapered fiber having a classical core while on top of its external surface, radially oriented nanorods are disposed. The tails of the propagated wave are interacting with those radially oriented nanorods. This interaction performs the polarization of the propagated mode into a radial polarization.     

Effect of fullerene coating on silicon thin film anodes for lithium rechargeable batteries

To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy. The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g⁻¹ as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the Li-ion kinetic property at the electrode/electrolyte interface.     

Quantum‐Dot‐Sensitized Solar Cells

Quantum‐dot‐sensitized solar cells (QDSCs) are a promising low‐cost alternative to existing photovoltaic technologies such as crystalline silicon and thin inorganic films. The absorption spectrum of quantum dots (QDs) can be tailored by controlling their size, and QDs can be produced by low‐cost methods. Nanostructures such as mesoporous films, nanorods, nanowires, nanotubes and nanosheets with high microscopic surface area, redox electrolytes and solid‐state hole conductors are borrowed from standard dye‐sensitized solar cells (DSCs) to fabricate electron conductor/QD monolayer/hole conductor junctions with high optical absorbance. Herein we focus on recent developments in the field of mono‐ and polydisperse QDSCs. Stability issues are adressed, coating methods are presented, performance is reviewed and special emphasis is given to the importance of energy‐level alignment to increase the light to electric power conversion efficiency.     

New pseudopolynomial complexity bounds for the bounded and other integer Knapsack related problems

We consider the bounded integer knapsack problem (BKP) , subject to: , and x_j{0,1,…,m_j},j=1,…,n. We use proximity results between the integer and the continuous versions to obtain an O(n³W²) algorithm for BKP, where W=max_j=1,…,nw_j. The respective complexity of the unbounded case with m_j=∞, for j=1,…,n, is O(n²W²). We use these results to obtain an improved strongly polynomial algorithm for the multicover problem with cyclical 1’s and uniform right-hand side.