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1.
This paper presents two new higher order diffusion models for removing noise from images. The models employ fractional derivatives
and are modifications of an existing fourth order partial differential equation (PDE) model which was developed by You and
Kaveh as a generalization of the well-known second order Perona-Malik equation. The modifications serve to cure the ill-posedness
of the You-Kaveh model without sacrificing performance. Also proposed in this paper is a simple smoothing technique which
can be used in numerical experiments to improve denoising and reduce processing time. Numerical experiments are shown for
comparison. 相似文献
2.
Kholdeeva Oxana A. Ivanchikova Irina D. Maksimchuk Nataliya V. Melgunov Maxim S. Chang Jong-San Guidotti Matteo Shutilov Alexei A. Zaikovskii Vladimir I. 《Topics in Catalysis》2014,57(17):1377-1384
Catalytic properties of Ti-containing porous solids were compared in the oxidation of 2,3,6-trimethylphenol (TMP) with H2O2 to produce 2,3,5-trimethyl-1,4-benzoquinone (TMBQ, vitamin E key intermediate). Mesoporous titanium–silicates with di(oligo)nuclear Ti centers, metal–organic framework MIL-125 and amorphous TiO2 demonstrated 100 % selectivity toward TMBQ. Titanium–silicates prepared by evaporation-induced self-assembly revealed superior performance in terms of product yield and catalyst reusability.
相似文献3.
IM Bell JM Erb RM Freidinger SN Gallicchio JP Guare MT Guidotti RA Halpin DW Hobbs CF Homnick MS Kuo EV Lis DJ Mathre SR Michelson JM Pawluczyk DJ Pettibone DR Reiss S Vickers PD Williams CJ Woyden 《Canadian Metallurgical Quarterly》1998,41(12):2146-2163
The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases. 相似文献
4.
A kinetics study of the reduction of Nb2O5 with NH3 was conducted at 600° to 1300°C, using vertical fixed-bed, flow-through reactors, with the goal of using the nitride as an
interme-diate in the preparation of niobium (columbium) metal via a thermal decomposition step. The effects of reactor materials
(stainless steel, nickel, molybdenum, graphite, alumina, and Vycor) upon ammonia reactivity toward Nb2O5 were investigated. At low temperatures, the metal reactor systems were more catalytically reactive, yielding faster rates
of reac-tion and a greater degree of nitride conversion, whereas at high temperatures, the non-metal reactor systems performed
better. In general, the initial reaction rate-temperature data exhibited a maximum, associated with oxynitride formation,
near 700°C for the metal reactor systems and 800° to 900°C for the nonmetal reactor systems, followed by a mini-mum, associated
with NbO2 formation, at 800° to 850°C for the metal reactor systems and 950° to 1000°C for the nonmetal reactor systems where NbN formation
commences. A sec-ond maximum, associated with the hexagonal NbN phase, occurred at 1200°C. The ranges of activation energies
for these regions were from 15 to 30 kcal/mole for region I, 8 to 22 kcal/mole for region II, and 10 to 22 kcal/mole for region
III. 相似文献
5.
6.
This article gives an overview of the important properties and design characteristics of electrolyte used in thermally activated (thermal) batteries. The basic physical properties of the main compositions are reviewed. The properties of electrolytes such as melting point, ionic conductivity, surface tension, density, thermal characteristics, and moisture sensitivity were analyzed in relation with the functioning of the batteries. Solubility data of alkali metals, sulphides, and oxides were compiled and analyzed. The important parameters of separator pellets are discussed in terms of both electrical and mechanical properties as they pertain to thermal-battery design and functioning. A number of lower-melting electrolytes are presented along with key physical properties for possible use in applications requiring lower operating temperatures such as borehole power supplies. 相似文献
7.
We have shown that ecto-apyrase protein is expressed in primary neurons and astrocytes in cell culture (T.-F. Wang, P.A. Rosenberg, G. Guidotti, 1997. Mol. Brain Res. 1997, 47: 295-302). Here we present immunohistochemical studies showing that ecto-apyrase protein is widely distributed in rat brain, as it is present in neurons of the cerebral cortex, hippocampus and cerebellum as well as in glial cells and endothelial cells. Ecto-apyrase is enriched in brain postsynaptic density membrane fractions and is localized in proximity to synaptophysin, the marker of synaptic vesicles. These results together with the observation that P2 purinergic receptors are present throughout the brain suggest that ecto-apyrase is involved in regulating synaptic transmission mediated by extracellular ATP. 相似文献
8.
9.
10.
Interleukin-12 (IL-12) is a heterodimeric cytokine produced by antigen-presenting cells that has the ability to induce gamma interferon (IFN-gamma) secretion by T and natural killer cells and to generate normal Th1 responses. These properties suggest that IL-12 may play an important role in the immune response to many viruses, including hepatitis B virus (HBV). Recently, we have shown that HBV-specific cytotoxic T lymphocytes inhibit HBV replication in the livers of transgenic mice by a noncytolytic process that is mediated in part by IFN-gamma. In the current study, we demonstrated that the same antiviral response can be initiated by recombinant murine IL-12 and we showed that the antiviral effect of IL-12 extends to extrahepatic sites such as the kidney. Southern blot analyses revealed the complete disappearance of HBV replicative intermediates from liver and kidney tissues at IL-12 doses that induce little or no inflammation in these tissues. In addition, immunohistochemical analysis demonstrated the disappearance of cytoplasmic hepatitis B core antigen from both tissues after IL-12 treatment, suggesting that IL-12 either prevents the assembly or triggers the degradation of the nucleocapsid particles within which HBV replication occurs. Importantly, we demonstrated that although IFN-gamma, tumor necrosis factor alpha, and IFN-alpha/beta mRNA are induced in the liver and kidney after IL-12 administration, the antiviral effect of IL-12 is mediated principally by its ability to induce IFN-gamma production in this model. These results suggest that IL-12, through its ability to induce IFN-gamma, probably plays an important role in the antiviral immune response to HBV during natural infection. Further, since relatively nontoxic doses of recombinant IL-12 profoundly inhibit HBV replication in the liver and extrahepatic sites in this model, IL-12 may have therapeutic value as an antiviral agent for the treatment of chronic HBV infection. 相似文献