Selective syntheses of 3,4-vinylenedithiathiophenes (VDTTs) and dithieno[2,3-b;2′,3′-d]thiophenes (DTTs), having Ph, 4-CH3OC6H4, 4-BrC6H4, 4-NO2C6H4 and 4-(CH3)2NC6H4 groups, were achieved through the reaction of 1,8-diketone with phosphorus decasulfide (P4S10). The reaction could be shifted between VDTT and DTT by adding base (sodium bicarbonate) or acid (para-toluenesulfonic acid), respectively, to the reaction mixture. While the VDTTs were obtained in moderate yields, an important achievement has been made with the syntheses of the DTTs, obtaining them in higher yields compared with the previous report. Polymers of the VDTTs, which are the analogues of ethylenedioxythiophene, EDOT, were prepared using FeCl3. Unfortunately, all attempts for their electropolymerization failed. Spin density calculations revealed that none of the VDTTs had a significant positive spin density at the ‘α’ carbon atoms of the thiophene ring. Considering their solubility and functional groups, which could be further derivatized, they are useful building blocks for the preparation of new organic materials. 相似文献
We study a selective and periodic inventory routing problem (SPIRP) and develop an Adaptive Large Neighborhood Search (ALNS) algorithm for its solution. The problem concerns a biodiesel production facility collecting used vegetable oil from sources, such as restaurants, catering companies and hotels that produce waste vegetable oil in considerable amounts. The facility reuses the collected waste oil as raw material to produce biodiesel. It has to meet certain raw material requirements either from daily collection, or from its inventory, or by purchasing virgin oil. SPIRP involves decisions about which of the present source nodes to include in the collection program, and which periodic (weekly) routing schedule to repeat over an infinite planning horizon. The objective is to minimize the total collection, inventory and purchasing costs while meeting the raw material requirements and operational constraints. A single-commodity flow-based mixed integer linear programming (MILP) model was proposed for this problem in an earlier study. The model was solved with 25 source nodes on a 7-day cyclic planning horizon. In order to tackle larger instances, we develop an ALNS algorithm that is based on a rich neighborhood structure with 11 distinct moves tailored to this problem. We demonstrate the performance of the ALNS, and compare it with the MILP model on test instances containing up to 100 source nodes. 相似文献
We study the stochastic lot-sizing problem with service level constraints and propose an efficient mixed integer reformulation thereof. We use the formulation of the problem present in the literature as a benchmark, and prove that the reformulation has a stronger linear relaxation. Also, we numerically illustrate that it yields a superior computational performance. The results of our numerical study reveals that the reformulation can optimally solve problem instances with planning horizons over 200 periods in less than a minute. 相似文献
The reaction of [RuCl(2)(p-cymene](2) with Ag-N-heterocyclic carbene (NHC) complexes yields a series of [(p-cymene)Ru(NHC)] complexes (2a-f). All synthesised compounds were characterized by elemental analysis, NMR spectroscopy and the molecular structure of 2a was determined by X-ray crystallography. All complexes have been tested as catalysts for the transfer hydrogenation of aromatic ketones, showing excellent activity in this reaction. 相似文献
Synchrotron based photoemission electron microscopy with energy filter combines real space imaging with microprobe diffraction (μ-ARPES), giving access to the local electronic structure of laterally inhomogeneous materials. We present here an overview of the capabilities of this technique, illustrating selected applications of angle resolved photoemission electron microscopy and related microprobe methods. In addition, we report the demonstration of a darkfield XPEEM (df-XPEEM) imaging method for real space mapping of the electronic structure away from Γ at a lateral resolution of few tens of nm. The application of df-XPEEM to the (1 × 12)-O/W(1 1 0) model oxide structure shows the high sensitivity of this technique to the local electronic structure, allowing to image domains with inequivalent adsorption site symmetry. Perspectives of angle-resolved PEEM are discussed. 相似文献
Coumarilate–nicotinamide complexes of CoII and ZnII were synthesized and investigated by elemental analysis, magnetic susceptibility, solid state UV–Vis, direct injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA, and crystal X-ray diffraction methods. It was obtained that both complex structures contain 2 mol aqua ligands, 2 mol coumarilate (CCA?) and 2 mol nicotinamide (NA) ligands per formula unit. The CCA? and NA ligands were bonded to metal cations as monodentate through acidic oxygen and nitrogen of pyridine ring, respectively. Thermal decomposition of each complex starts with dehydration and continue removing of 1 mol NA ligand. The thermal dehydration of the complexes takes place in one or two steps. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The final decomposition products are found to be metal oxides. 相似文献
During the last decade, there has been a rapidly growing trend toward the use of cellphone-based devices (CBDs) in bioanalytical sciences. For example, they have been used for digital microscopy, cytometry, read-out of immunoassays and lateral flow tests, electrochemical and surface plasmon resonance based bio-sensing, colorimetric detection and healthcare monitoring, among others. Cellphone can be considered as one of the most prospective devices for the development of next-generation point-of-care (POC) diagnostics platforms, enabling mobile healthcare delivery and personalized medicine. With more than 6.5 billion cellphone subscribers worldwide and approximately 1.6 billion new devices being sold each year, cellphone technology is also creating new business and research opportunities. Many cellphone-based devices, such as those targeted for diabetic management, weight management, monitoring of blood pressure and pulse rate, have already become commercially-available in recent years. In addition to such monitoring platforms, several other CBDs are also being introduced, targeting e.g., microscopic imaging and sensing applications for medical diagnostics using novel computational algorithms and components already embedded on cellphones. This report aims to review these recent developments in CBDs for bioanalytical sciences along with some of the challenges involved and the future opportunities.
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The universal Rapid Diagnostic Test (RDT) reader developed at UCLA. It can read various lateral flow assays for point-of-care and telemedicine applications 相似文献
A new rapid and sensitive method has been developed and validated for the simultaneous determination of phenylephrine hydrochloride, paracetamol, chlorpheniramine maleate and dextromethorphan hydrobromide in pharmaceutical preparations. The separation was achieved on a C18 column using a gradient mobile phase of acetonitrile–sodium perchlorate (pH 3, 0.01 M) at a flow rate of 1.4 mL min−1. Detection was at 204 nm. Pseudoephedrine hydrochloride was selected as internal standard. The recovery of the drugs ranged from 97.8 to 100.9%. Central composite design was used during validation to calculate method robustness and the percentage of sodium perchlorate, temperature and flow rate were investigated as factors. The method was found to be applicable for the determination of the four compounds in sugar-coated tablets.
Presented in this paper are the results of natural convection heat transfer between inclined parallel plates. Lower plate is heated isothermally while the upper plate is both unheated and insulated. Plate inclinations were 0°, 30°, 45° measured from vertical position. Experiments were carried out for different temperature differences in air to determine the effect of plate spacing and plate inclination on heat transfer. It was found that heat transfer rate depends on plate spacing and inclination. 相似文献