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181.
On Dialkali Metal Dichalcogenides β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 and Rb2Te2 The first presentation of pure samples of α- and β-Rb2S2, α- and β-K2Te2, and Rb2Te2 is described. Using single crystals of K2S2 and K2Se2, received by ammonothermal synthesis, the structure of the Na2O2 type and by using single crystals of β-Na2S2 and β-K2Te2 the Li2O2 type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na2O2 type to the Li2O2 type will be explained by means of the examples α-/β-Na2S2 and α-/β-K2Te2. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb2S2 is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence. 相似文献
182.
A New Tricyclic Sulfur-rich Phosphane From the products of the reaction of P4S3 with tert-Butyliodide the compound (t-Bu(S)P)2P4S3 was isolated in low yield. The compound is stable and has a structure related to the hydrocarbon brexane. By reaction with triphenylphosphin the compounds (t-BuP)(t-Bu(S)P)P4S3 and (t-BuP)2P4S3 were obtained. The 31P-nmr spectra of all compounds were solved and used to determine the structure of the molecules. A complete set of 31P-nmr data is given. 相似文献
183.
Preparation of the Iminium Salts CF3? NX?CF2+MF6? (X = CH3, F and M = As, Sb) and CF3? NCl?CF2+ AsF6? The preparation of the iminiumsalts CF3? NX?CF2+ MF6? (X = CH3, F and M = As, Sb) and CF3? NCl?CF2+ AsF6? is reported. The salts were characterized by NMR and infrared spectroscopy. CF3? NCH3?CF2+MF6? decompose into MF5 and (CF3)2NCH3. 相似文献
184.
《Journal of Coordination Chemistry》2012,65(8):1358-1368
An organic–inorganic hybrid compound (C5H9N3)ZnCl4 · H2O was synthesized by slow evaporation and characterized by single-crystal X-ray diffraction, differential scanning calorimetry, thermogravimetry, temperature-dependent X-ray powder diffraction, infrared spectroscopy, and some preliminary theoretical calculations of non-linear optic activity. The compound crystallizes in the non-centrosymmetric space group Pca21 with unit cell parameters: a = 22.714(5), b = 7.313(5), c = 7.301(5) Å, Z = 4, and V = 1212.8(12) Å3. The structure was solved using direct methods and refined by least-squares analysis [R 1 = 0.0484 and wR 2 = 0.1255]. It is built from isolated [ZnCl4]2? anions, 2,5-diaminopyridinediium [C5H9N3]2+ cations, and water molecules which are connected by a 3-D hydrogen-bond network. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through four stages leading to a new crystalline anhydrous phases. 相似文献
185.
Camila L. de Camargo Letícia S. ShiromaGabriela F. Giordano Angelo L. GobbiLuis C.S. Vieira Renato S. Lima 《Analytica chimica acta》2016
This paper addresses an important breakthrough in the deployment of ultra-high adhesion strength microfluidic technologies to provide turbulence at harsh flow rate conditions. This paper is only, to our knowledge, the second reporting on the generation of high flow rate-assisted turbulence in microchannels. This flow solves a crucial bottleneck in microfluidics: the generation of high throughput homogeneous mixings. We focused on the fabrication of bulky polydimethylsiloxane (PDMS) microchips (without any interfaces) rather than the laborious surface modifications that were employed in the first reporting about turbulence-assisted microfluidics. The fabrication is cleanroom-free, simple, low-cost, fast, solventless, and bondless requiring only a laboratory oven. More specifically, our method relies on the shaping of a nylon scaffold, cure of PDMS with embedded nylon, and removal of this scaffold. The scaffold was obtained by manually wrapping nylon threads. The withdrawing out of the scaffold was completed in few seconds using only a plier. Such microchannels endured flow rates of up to 60.0 mL min−1 with a strikingly low elastic deformation. The importance in producing turbulence into microscale channels was successfully shown in liquid-liquid extractions. The great energy dissipation rate relative to the turbulence created high throughput and efficient extractions in microfluidics for the first time. The residence time was only 0.01 s at 25.0 mL min−1 (total flow rate of the immiscible phases). In addition, the partition coefficient determined in a single run was similar to that obtained by the conventional batch shake-flask method that was realized in triplicate. 相似文献
186.
Aldoximes are readily dehydrated to nitriles with Raney nickel in refluxing 2-propanol. 相似文献
187.
Giovana Ferronato Mariela S. Viera Osmar D. Prestes Martha B. Adaime 《International journal of environmental analytical chemistry》2013,93(11):1005-1016
ABSTRACTThe food chain is the main source of exposure to humans by organochlorine pesticides (OCPs) due to the bioaccumulation. Breast milk can accumulate OCPs, so this matrix is often used as an environmental bioindicator. The currently available methods for the determination of several OCPs and metabolites in breast milk involve, in general, multi-step sample preparation and quantification techniques with low selectivity, high cost and much time and labour. Thus, a fast and efficient method based on sample preparation using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with gas chromatography coupled to mass spectrometry with negative chemical ionisation (GC-NCI-MS) was developed, validated and applied for determination of 16 OCPs and metabolites in breast milk samples. The extract was cleaned by dispersive solid-phase extraction (d-SPE) using MgSO4 and C18, evaporated in a Turbovap® system, redissolved and analysed by GC-NCI-MS. The method was validated showing acceptable recoveries (72–118%) and precision (RSD <19%). Method limits of detection (LODs) and quantification (LOQs) ranged from 0.75 to 7.5 ng g?1 and from 2.5 to 25 ng g?1 lipid, respectively. The method was successfully applied to 20 samples of breast milk from different regions of the Rio Grande do Sul state, Brazil, of which 75% contained residues below the LOQs. 相似文献
188.
Yanzhen Guo Qian Yang Wei Yan Bing Li Tian Li 《International journal of environmental analytical chemistry》2013,93(10):1001-1012
Acetochlor is an important herbicide for gramineous weeds and some small seed broadleaf weeds. Controlled-release formulations of herbicide are highly desirable not only for attaining the most effective utilisation of the weed control, but also for reducing environmental pollution. Acetochlor was incorporated in poly (butyl methacrylate-diacetone acrylamide) based formulation to obtain controlled release properties. The acetochlor nanocapsules were characterised by size distribution, infrared spectroscopy (IR) and field emission scanning electron microscopy (FESEM), and factors related to loading efficiency, swelling behaviour of the formulation were investigated. For this controlled-release formulation, the loading efficiency could reach about 50% (w/w). n, the diffusion parameter was indicative of the transport mechanism, and the values for ‘n’ were in the range of 0.28–0.61, which indicated that the release of acetochlor was diffusion-controlled. The time taken for 50% of the active ingredient to be released into water, t50, was also calculated for the comparison of formulations in different conditions. The formulation with higher temperature and more diacetone acrylamide had lower value of t50, which means a quicker release of the active ingredient. This study highlighted some pieces of evidence that improved herbicide incorporation and slower release were linked to potential interactions between the herbicide and the polymer. 相似文献
189.
K. Wetzel 《Isotopes in environmental and health studies》2013,49(3):125-126
In einem dynamischen System vollziehen sich kontinuierlich ablaufende Stoffwandlungen, deren Ausgangsstoffe dem System ständig zufließen und deren Folgeprodukte das System kontinuierlich verlassen. Es wird das Verhalten eines solchen Systems mit drei Pools bei Markierungsexperimenten untersucht. Die Ergebnisse dieser mathematischen Untersuchungen werden auf die Erforschung des Stickstoffstoffwechsels laktierender Rinder mit Hilfe des stabilen Isotops 15N angewandt. In diesem Fall enthält das dynamische System zwei kleine stoffwechselaktive Pools und einen großen, niclit intensiv am Stoffwechsel beteiligten Körpereiweiβ-Pool. 相似文献
190.
We construct a quantum circuit to produce a task-oriented partially entangled state and use it as the quantum channel for controlled joint remote state preparation. Unlike most previous works, where the parameters of the quantum channel are given to the receiver who can accomplish the task only probabilistically by consuming auxiliary resource, operation and measurement, here we give them to the supervisor. Thanks to the knowledge of the task-oriented quantum channel parameters, the supervisor can carry out proper complete projective measurement, which, combined with the feed-forward technique adapted by the preparers, not only much economizes (simplifies) the receiver's resource (operation) but also yields unit total success probability. Notably, such apparent perfection does not depend on the entanglement degree of the shared quantum channel. Our protocol is within the reach of current quantum technologies. 相似文献