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1.
Roberto Lava Emilia Aimo Luciana Menegus Giulio Pojana Antonio Marcomini 《Analytica chimica acta》2013
Two simple analytical methods for the simultaneous determination and quantification of benzotrifluoride and eight chlorinated, amino and nitro benzotrifluoride derivatives in groundwater are proposed. Benzotrifluoride, 4-chlorobenzotrifluoride, 2,4-dichlorobenzotrifluoride and 3,4-dichlorobenzotrifluoride, were extracted by Purge-and-Trap on the basis of their volatile properties, while 3-aminobenzotrifluoride, 4-nitrobenzotrifluoride, 3-amino-4-chlorobenzotrifluoride, 3-nitro-4-chlorobenzotrifluoride and 4-chloro-3,5-dinitrobenzotrifluoride extractions were done with an automated SPE system. The analytical separations and detections were performed with two different GC systems, both equipped with single quadrupole mass spectrometer as detector. The LOD ranges for the two methods were 0.002–0.005 μg L−1 and 0.01–0.07 μg L−1, respectively. Both extraction methods were developed using spiked Milli-Q water and were then demonstrated with groundwater samples collected during autumn 2008. The areas of groundwater collection were polluted due to an episode of improper industrial soil disposal and consequent leakage of aliphatic and aromatic, fluorinated chemicals into the groundwater. This work eventually revealed the presence of several benzotrifluoride compounds most of them, like dichloro- and amino-derivatives, never been reported as environmental contaminants. 相似文献
2.
Aimo Hinkkanen 《Mathematische Zeitschrift》1983,183(4):539-545
3.
Pekka Kekäläinen Mikko Voutilainen Antti Poteri Pirkko Hölttä Aimo Hautojärvi Jussi Timonen 《Transport in Porous Media》2011,87(1):125-149
A model transport system is considered in which a pulse of tracer molecules is advected along a flow channel with porous walls.
The advected tracer thus undergoes diffusion, matrix-diffusion, inside the walls, which affects the breakthrough curve of
the tracer. Analytical solutions in the form of series expansions are derived for a number of situations which include a finite
depth of the porous matrix, varying aperture of the flow channel, and longitudinal diffusion and Taylor dispersion of the
tracer in the flow channel. Novel expansions for the Laplace transforms of the concentration in the channel facilitated closed-form
expressions for the solutions. A rigorous result is also derived for the asymptotic form of the breakthrough curve for a finite
depth of the porous matrix, which is very different from that for an infinite matrix. A specific experimental system was created
for validation of matrix-diffusion modeling for a matrix of finite depth. A previously reported fracture-column experiment
was also modeled. In both cases model solutions gave excellent fits to the measured breakthrough curves with very consistent
values for the diffusion coefficients used as the fitting parameters. The matrix-diffusion modeling performed could thereby
be validated. 相似文献
5.
Aimo Kannt Sridharan Rajagopal Mahanandeesha S. Hallur Indu Swamy Rajendra Kristam Saravanakumar Dhakshinamoorthy Joerg Czech Gernot Zech Herman Schreuder Sven Ruf 《Molecules (Basel, Switzerland)》2021,26(4)
Nicotinamide-N-methyltransferase (NNMT) is a cytosolic enzyme catalyzing the transfer of a methyl group from S-adenosyl-methionine (SAM) to nicotinamide (Nam). It is expressed in many tissues including the liver, adipose tissue, and skeletal muscle. Its expression in several cancer cell lines has been widely discussed in the literature, and recent work established a link between NNMT expression and metabolic diseases. Here we describe our approach to identify potent small molecule inhibitors of NNMT featuring different binding modes as elucidated by X-ray crystallographic studies. 相似文献
6.
Let f be a polynomial of degree at least 2 with f(0)=0 and f′(0)=1. Suppose that all the zeros of f′ are real. We show that there is a zero ζ of f′ such that |f(ζ)/ζ|≤2/3, and that this inequality can be taken to be strict unless f is of the form f(z)=z+cz
3. 相似文献
7.
8.
Aimo Törn 《BIT Numerical Mathematics》1966,6(4):339-346
After a short discussion of Monte Carlo integration the crude Monte Carlo method is tested by estimating the integrals
$$\int\limits_0^1 {\left( {\frac{1}{x}} \right)^{1/v} } dxas\bar f_n = \frac{1}{n}\sum\limits_{i = 1}^n {\left( {\frac{1}{{\xi _i }}} \right)^{1/v} ,} $$ 相似文献
9.
Aimo A. Törn 《BIT Numerical Mathematics》1984,24(3):317-332
A hash structure, Overflow Indexing (OVI), using an index for the overflows is presented. The index contains one entry (key, bucket number) for each overflow. Formulas for computing the expected number of entries in the index and the standard deviation are derived and the numerical results obtained using these formulae are presented in a graph. It is concluded that storing the index in the main memory when operating on the file is feasible for small to medium-sized, and sometimes even large files. The number of probes for both a successful and unsuccessful search is one. Deletion requires two probes and insertion two or three probes. Details of OVI are presented and illustrated by simulation experiments. The structure of the index is discussed and one possible structure, hashing with dynamic buckets, is presented. 相似文献
10.
In an interferometric pump-probe experiment, we demonstrate the phase tuning of the spin polarization of photoelectrons emitted in a three-photon process from Cu(001). A phase shift of pi between delayed ultrafast circularly polarized light pulses can switch the spin polarization from +/-20% to -/+40%. In the delay regime of overlapping pulses, we show the dominating role of optical interference effects in determining the spin polarization. For longer delays, we detect the influence of the coherent material response, manifested in both the final state electron population as well as the final state spin polarization. 相似文献