Isotopic fractionation in thin-layer chromatography.

The thin-layer chromatography of imipramine on silica gel plates was studied in fifteen solvent systems. The mobility of imipramine labeled with deuterium in the methyl groups of the dimethylaminopropyl side chain differs markedly from that of unlabeled imipramine. Partial or complete separations between unlabeled and deuterated imipramine were observed in all basic and neutral solvent systems investigated, but not in weakly acidic solvents. Isotopic fractionations of imipramine were also found on alumina thin-layer plates, but were not detected in cellulose chromatography. In all thin-layer isotopic separations, the unlabeled compound migrates more rapidly than the deuterated molecule. These results can be explained by a stronger basicity of deuterated imipramine relative to its unlabeled counterpart.     

Bent partitions

Designs, Codes and Cryptography - Spread and partial spread constructions are the most powerful bent function constructions. A large variety of bent functions from a 2m-dimensional vector space...     

An experimental investigation on performance of rectangular fins on a horizontal base in free convection heat transfer

This paper reports an experimental study of free convection heat transfer from rectangular fin-arrays on a horizontal base. An experimental set-up was constructed and calibrated, 15 sets of fin-arrays and a base plate without fins were tested in atmosphere. Fin height was varied from 6 mm to 26 mm, fin spacing was varied from 6.2 mm to 83 mm. The base-to-ambient temperature difference was also varied independently and systematically with the power supply to heater ranging from 8 W to 50 W. Fin length and fin thicknesses were fixed at 100 mm and 3 mm, respectively. The experimental program was conducted so as to clearly delineate the separate roles of fin height, fin spacing and base-to-ambient temperature difference. It was found that for a given base-to-ambient temperature difference the convection heat transfer rate from fin-arrays takes on a maximum value as a function of fin spacing and fin height. For a given base-to-ambient temperature difference the enhancement of the convection heat transfer rate of fin-arrays relative to that for base plate without fins is strongly dependent on the fin spacing to fin height ratio and number of fins. A correlation was also presented relating the convection heat transfer rate of fin-arrays relative to that for base plate without fins with the relevant non-dimensional parameters. Received on 7 August 1997     

A one-shot bargaining problem

There are bargaining situations in which the parties cannot arrive at an agreement through negotiations but rather must make one irreversible claim which may or may not be fulfilled. In this paper we discuss a model for such a “one-shot bargaining”.     

Density functional theory analysis of molybdenum isotope fractionation

Analytical studies have found an enrichment of the lighter Mo isotopes in oxic marine sediments compared to seawater, with isotope fractionation factors of -1.7 to -2.0 per thousand for Delta97/95Mosediment-seawater. These data place constraints on the possible identities of dissolved and adsorbed species because the equilibrium isotope fractionation depends on the energy differences between the isotopomers of the adsorbed species, minor dissolved species, and the dominant solution species, MoO42-. Adsorption likely involves molybdic acid, whose structure is indicated by previous studies to be MoO3(H2O)3. Here we used DFT calculations of vibrational frequencies to determine the isotope fractionation factors versus MoO42-. The results indicate that isotope equilibration of MoO42- with MoO3(H2O)3, yielding Delta97/95Momolybdic acid-molybdate=-1.33 per thousand, is most likely responsible for the isotope fractionation of Mo between oxic sediments and seawater. The difference between the calculated value of Delta97/95Momolybdic acid-molybdate for MoO3(H2O)3 and the value observed in natural sediments and experiments is probably due to effects of solvation and adsorption onto the manganese oxyhydroxide surface.     

Idempotent and <Emphasis Type="Italic">p</Emphasis>-potent quadratic functions: distribution of nonlinearity and co-dimension

The Walsh transform \(\widehat{Q}\) of a quadratic function \(Q:{\mathbb F}_{p^n}\rightarrow {\mathbb F}_p\) satisfies \(|\widehat{Q}(b)| \in \{0,p^{\frac{n+s}{2}}\}\) for all \(b\in {\mathbb F}_{p^n}\), where \(0\le s\le n-1\) is an integer depending on Q. In this article, we study the following three classes of quadratic functions of wide interest. The class \(\mathcal {C}_1\) is defined for arbitrary n as \(\mathcal {C}_1 = \{Q(x) = \mathrm{Tr_n}(\sum _{i=1}^{\lfloor (n-1)/2\rfloor }a_ix^{2^i+1})\;:\; a_i \in {\mathbb F}_2\}\), and the larger class \(\mathcal {C}_2\) is defined for even n as \(\mathcal {C}_2 = \{Q(x) = \mathrm{Tr_n}(\sum _{i=1}^{(n/2)-1}a_ix^{2^i+1}) + \mathrm{Tr_{n/2}}(a_{n/2}x^{2^{n/2}+1}) \;:\; a_i \in {\mathbb F}_2\}\). For an odd prime p, the subclass \(\mathcal {D}\) of all p-ary quadratic functions is defined as \(\mathcal {D} = \{Q(x) = \mathrm{Tr_n}(\sum _{i=0}^{\lfloor n/2\rfloor }a_ix^{p^i+1})\;:\; a_i \in {\mathbb F}_p\}\). We determine the generating function for the distribution of the parameter s for \(\mathcal {C}_1, \mathcal {C}_2\) and \(\mathcal {D}\). As a consequence we completely describe the distribution of the nonlinearity for the rotation symmetric quadratic Boolean functions, and in the case \(p > 2\), the distribution of the co-dimension for the rotation symmetric quadratic p-ary functions, which have been attracting considerable attention recently. Our results also facilitate obtaining closed formulas for the number of such quadratic functions with prescribed s for small values of s, and hence extend earlier results on this topic. We also present the complete weight distribution of the subcodes of the second order Reed–Muller codes corresponding to \(\mathcal {C}_1\) and \(\mathcal {C}_2\) in terms of a generating function.     

Mechanical properties and transition temperatures of cross-linked oriented gelatin

This study is an extension of previous work on cellulosics [(1994)Colloid Polym Sci 272: 284, 393] that showed that unusually good mechanical properties can be obtained by drying a swollen network of semirigid chains in a state of strain. This novel approach is applied in this investigation to gelatin, because of its attractive environmental characteristics but poor mechanical properties in the unmodified form. Since drawing of non-crosslinked gelatin is not practical, crosslinking by formaldehyde was used, followed by swelling, drawing and drying at fixed length. Mechanical tests were performed in static and dynamic modes. In this way improvements of Young's modulusE, and stress at break _b were determined as a function of gelatin concentration during drying. An increase inE and _b up to 2–3 times, and in the dynamic modulusE up to 6 times, was obtained when the draw ratio reached 4–5, after whichE, E, and _b were found to decrease. Such behavior is explained by the highest orientation being achieved at =4–5, as proved by x-ray analysis. At =10–20 the orientation is lost due to relaxation of chain segments, which is preceded by partial destroying of the network structure (chemical and physical), possibly via chain scission, but probably mostly by the pulling out of chains from crystallites. In any case, the mechanical properties become poor again.The improvements reported above were referred to the undrawn but crosslinked gelatin. Compared to the starting isotropic non-crosslinked material, the improvement is slightly higher. The observation that the improvements are less than those obtained for the cellulosics is explained by the coexistence of interpenetrating chemical and physical networks, which is typical of gelatin. This structural feature drastically reduces the orientability of the chains and the improvements that can be expected in the mechanical properties.     

Evaluation of Substituted Pyrazole-Based Kinase Inhibitors in One Decade (2011–2020): Current Status and Future Prospects

Pyrazole has been recognized as a pharmacologically important privileged scaffold whose derivatives produce almost all types of pharmacological activities and have attracted much attention in the last decades. Of the various pyrazole derivatives reported as potential therapeutic agents, this article focuses on pyrazole-based kinase inhibitors. Pyrazole-possessing kinase inhibitors play a crucial role in various disease areas, especially in many cancer types such as lymphoma, breast cancer, melanoma, cervical cancer, and others in addition to inflammation and neurodegenerative disorders. In this article, we reviewed the structural and biological characteristics of the pyrazole derivatives recently reported as kinase inhibitors and classified them according to their target kinases in a chronological order. We reviewed the reports including pyrazole derivatives as kinase inhibitors published during the past decade (2011–2020).