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61.
62.
S. A. El-Reefy J. A. Daoud H. F. Aly 《Journal of Radioanalytical and Nuclear Chemistry》1992,158(2):303-312
It is found that from aqueous nitric acid media, Pd is highly extracted by chloroform solutions containing triphenylphosphine (Ph3P) and not extracted by triphenylphosphine oxide (Ph3PO) diluted with chloroform. The effect of diluent, nitric acid molarities, Ph3P concentration and temperature on palladium extraction by Ph3P was investigated. Slope analysis of the experimental results indicated that the main extracted species is in the form of Pd(NO3)2·2Ph3P.IR spectrum analysis of the extracted complex indicated the direct extraction of palladium as nitrate and bonding to phosphorus. Extraction of some fission product radionuclides from 2M HNO3 showed the selective extraction of palladium by Ph3P in chloroform. 相似文献
63.
Vapor pressure is one of the fundamental properties which govern the distribution of organic compounds in the environment. This property is estimated for five series of homologous substituted alkanes of the type H—(CH2)n—Y, where Y denotes Cl, Br, CHO, COOCH3, OCOCH3 and n varies from 5 to 14 using extrapolation of adjusted retention times to 25 °C. The results are compared with those obtained by using indirect methods for 40 compounds and a significant improvement is obtained. Indeed, the absolute average error percentage for the same series does not exceed 2.6% 相似文献
64.
Alexandre Campos Moraes Daniel Benevides da Costa Michel Daoud Yacoub 《Wireless Personal Communications》2012,64(1):3-19
Wireless communications systems in a frequency reuse environment are subject to cochannel interference. In order to improve
the system performance, diversity techniques are deployed. Among the practical diversity schemes used, Equal-Gain Combining
(EGC) appears as a reasonably simple and effective one. Unfortunately, the exact analysis of the outage probability of EGC
receivers is rather intricate for it involves the evaluation of multifold nested integrals. It becomes mathematically intractable
with the increase of the number of diversity branches and/or interferers. For example, for N
B
diversity branches and N
I
arbitrary independent cochannel interferers, the exact formulation using the convolutional approach requires 2 + N
B
+ (N
B
× N
I
) nested integrals, which, very quickly, and for any practical system, turns out to be mathematically intractable. In this
paper, we propose accurate approximate formulations for this problem, whose results are practically indistinguishable from
the exact solution. In our model, the system is composed by N
B
branches and N
I
interferers so that the desired signals are coherently summed, whereas the interfering signals are incoherently summed at
the EGC receiver. Three sets of fading scenarios, namely α-μ , κ-μ, and η-μ, are investigated. The proposed approach is indeed flexible and accommodates a variety of mixed fading scenarios for desired
and interfering signals. 相似文献
65.
This paper describes the physical models behind the various fading distributions applicable in wireless-communications systems, and presents the probability density functions, both for the signal envelope and for the power of the mobile radio signal. It addresses the problem of co-channel interference in terms of its mean value, for macrocellular and microcellular structures, and illustrates how the outage probability is influenced by a series of factors such as reuse pattern, modulation scheme, traffic load, and others 相似文献
66.
67.
68.
Jehad Almaliti Muhammed Alzweiri Momen Alhindy Tamam Al-Helo Ibrahim Daoud Raghad Deknash C. Benjamin Naman Bashaer Abu-Irmaileh Yasser Bustanji Islam Hamad 《Molecules (Basel, Switzerland)》2022,27(7)
Obesity is the most common nutritional disorder in the developed world and is associated with important comorbidities. Pancreatic lipase (PL) inhibitors play a key role in the metabolism of human fat. A series of novel epoxyketones peptide derivatives were investigated for their pancreatic lipase inhibitory activity. The epoxyketone moiety is a well-known reactive electrophile group that has been used as part of proteasome inhibitors in cancer therapy, and it is widely believed that these are very selective for targeting the proteasome active site. Here we investigated various peptide derivatives with an epoxide warhead for their anti-lipase activity. The assessment of these novel epoxyketones was performed by an in-house method that we developed for rapid screening and identification of lipase inhibitors using GC-FID. Herein, we present a novel anti-lipase pharmacophore based on epoxyketone peptide derivatives that showed potent anti-lipase activity. Many of these derivatives had comparable or more potent activity than the clinically used lipase inhibitors such as orlistat. In addition, the lipase appears to be inhibited by a wide range of epoxyketone analogues regardless of the configuration of the epoxide in the epoxyketone moiety. The presented data in this study shows the first example of the use of epoxyketone peptides as novel lipase inhibitors. 相似文献
69.
Houda Zendah Ismail Khattech Mohamed Jemal 《Journal of Thermal Analysis and Calorimetry》2012,109(2):855-861
A series of ??B?? type carbonate fluorapatites (B?CCO3?CFap) have been synthesized and characterized by X-ray diffraction, infrared spectroscopy, and chemical analysis. The thermochemical study of phosphoric acid attack of the products was performed by a 19% w/w P2O5 solution on raw and deconvoluted curves. The calculated thermogenesis curves show one, two, or four peaks, depending on the mass of dissolved solid and the carbonate content in B?CCO3?CFap. The plot of the quantity of heat measured by integrating the raw signal as a function of the dissolved mass in the same volume solution presents three straight segments for low-carbonated and two segments for moderately carbonated ones. From the slopes of line segments, it was possible to determine the enthalpies of dissolution of ??B?? type carbonate fluorapatites and to deduce that of precipitation of CaF2 and Ca(H2PO4)2·H2O, which have been compared to directly measured or literature data. 相似文献
70.
Cotinine levels in biological fluids are a reliable indicator of the presence of nicotine. In this paper, a simple and sensitive high-performance liquid chromatography (HPLC) procedure for the determination of cotinine in urine following liquid-liquid extraction with dichloromethane in an alkaline medium is described. Calibration curves show linearity over the 50 to 3000 ng/mL range with low intra- and interday variability as well as good selectivity and specificity. No solid-phase extraction is performed because the liquid dichloromethane extraction step yields excellent results. This method is a good alternative for routine analysis of urinary cotinine in laboratories where gas chromatography or HPLC-mass spectrometry is not available. 相似文献