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51.
Kiumars Kaveh Christopher Manon Takuya Murata 《Journal of Pure and Applied Algebra》2021,225(11):106713
We study the generic tropical initial ideals of a positively graded Cohen-Macaulay algebra R over an algebraically closed field k. Building on work of Römer and Schmitz, we give a formula for each initial ideal, and we express the associated quasivaluations in terms of certain I-adic filtrations. As a corollary, we show that in the case that R is a domain, every initial ideal coming from the codimension 1 skeleton of the tropical variety is prime, so “generic presentations of Cohen-Macaulay domains are well-poised in codimension 1.” 相似文献
52.
An efficient multi-step algorithm is presented for embedding a nonplanar graph on the least possible number of planes. In the first step, the graph is drawn on a plane with the smallest possible number of crossings. Then the appropriate crossing edges are selected and moved onto the second plane. This process is repeated introducing subsequent planes until no crossing remains. 相似文献
53.
The temperature dependence of the resistivity of (TMTSF)2PF6 over the temperature range 25–300 K is in excellent agreement with “libron” theory, if a Bloch (1-phonon) contribution corresponding to λ = 0.16 (a value determined from the Peierls transition temperature) is invoked. This contributes about 10% to the resistivity at 300 K, and about 20% at 40 K. 相似文献
54.
Jorabchi K Westphall MS Smith LM 《Journal of the American Society for Mass Spectrometry》2008,19(6):833-840
We propose and evaluate a new mechanism to account for analyte ion signal enhancement in ultraviolet-laser desorption mass spectrometry of droplets in the presence of corona ions. Our new insights are based on timing control of corona ion production, laser desorption, and peptide ion extraction achieved by a novel pulsed corona apparatus. We demonstrate that droplet charging rather than gas-phase ion-neutral reactions is the major contributor to analyte ion generation from an electrically isolated droplet. Implications of the new mechanism, termed charge assisted laser desorption/ionization (CALDI), are discussed and contrasted with those of the laser desorption atmospheric pressure chemical ionization method (LD-APCI). It is also demonstrated that analyte ion generation in CALDI occurs with external electric fields about one order of magnitude lower than those needed for atmospheric pressure matrix assisted laser desorption/ionization or electrospray ionization of droplets. 相似文献
55.
Mohammad Kaveh Yousef Abbaspour-Gilandeh Ebrahim Taghinezhad Dorota Witrowa-Rajchert Magorzata Nowacka 《Molecules (Basel, Switzerland)》2021,26(7)
Most agricultural products are harvested with a moisture content that is not suitable for storage. Therefore, the products are subjected to a drying process to prevent spoilage. This study evaluates an infrared rotary dryer (IRRD) with three levels of infrared power (250, 500, and 750 W) and three levels of rotation speed (5, 10, and 15 rpm) to dry terebinth. Response surface methodology (RSM) was used to illustrate and optimize the interaction between the independent variables (infrared power and rotation speed) and the response variables (drying time, moisture diffusivity, shrinkage, color change, rehydration rate, total phenolic content, and antioxidant activity). As infrared power and rotation speed increased, drying time, rehydration rate, antioxidant activity, and total phenolic content decreased, while the other parameters were increased. According to the results, the optimum drying conditions of terebinth were determined in the IRRD at an infrared power of 250 W and drum rotation speed of 5 rpm. The optimum values of the response variables were 49.5 min for drying time, 8.27 × 10−9 m2/s for effective moisture diffusivity, 2.26 for lightness, 21.60 for total color changes, 34.75% for shrinkage, 2.4 for rehydration rate, 124.76 mg GAE/g d.m. for total phenolic content and 81% for antioxidant activity. 相似文献
56.
Kaveh Khosravi Shirin Naserifar Boshra Mahmoudi Kobra Khalaji 《Phosphorus, sulfur, and silicon and the related elements》2017,192(3):316-321
A catalyst free and chemoselective oxidation of sulfides to sulfoxides or sulfones was developed using 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as a new oxidant. This scope has shown the achievement of various sulfoxides and sulfones which were obtained selectively in high yields at room temperature. 相似文献
57.
A bulk form of nanograined intermetallic Al3Ni was produced by severe plastic deformation using high-pressure torsion (HPT). Powder mixtures of 75?mol% Al and 25?mol% Ni were processed by HPT at a selected temperature in the range of room temperature (RT) to 573?K under a pressure of 6?GPa. X-ray diffraction analysis revealed that the Al3Ni intermetallic formed after processing for 50 revolutions at RT but, as the processing temperature increased, less revolutions (i.e. lower imposed strain) were required for the formation of Al3Ni. Observations by transmission electron microscopy showed that the microstructure consists of ultrafine grains having a size of 300–2000?nm after 3 and 10 revolutions. Once the Al3Ni formed after a higher number of revolutions, equiaxed nanograins with a size of ~30?nm prevailed with a significant increase in hardness. The increase in hardness was more significant when processed at higher temperatures because of increasing the fraction of Al3Ni. It was shown that the solid-state formation of Al3Ni occurred due to enhanced diffusion (i.e. decreased activation energy for diffusion) through the presence of high density of lattice defects. 相似文献
58.
Stable and non-hygroscopic silica gel supported aluminium chloride(SiO2-AlCl3),which is prepared easily from cheap and commercially available compounds was found to be an environmentally friendly heterogeneous catalyst for the condensation of indole with aldehydes and ketones to afford bis-indolylmethanes at room temperature under solvent-free conditions.The catalyst can be reused up to five times after simple washing with ether. 相似文献
59.
Kaveh Hariri Asli Faig Bakhman Ogli Naghiyev Akbar Khodaparast Haghi 《Nonlinear dynamics》2010,60(4):677-701
In this work, a computational method was used for the prediction of water transmission failure. The proposed method allowed
for any arbitrary combination of devices in the water pipeline system. The method used was by a scale model and a prototype
(real) system for a city main water pipeline where transient flow was caused by the failure of a transmission system. 相似文献
60.