Are axial and radial flow chromatography different?

Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable.     

Mathematical modeling of gas separation permeators — for radial crossflow,countercurrent, and cocurrent hollow fiber membrane modules

A new approach to solve the mass transfer problem posed by the permeation process in a hollow fiber permeator is presented and analyzed. The algorithm models the separation offered for a membrane module, for given gas conditions, simulating the permeate and residue composition and the stage cut. The advantage of the ‘succession of states’ approach utilized here is the option of retroactive incorporation of more complex interactions such as permeate pressure buildup, a pressure, composition and temperature dependent permeability. The two dimensional mass transfer in a radial crossflow permeator has been qualitatively discussed in the past, but it has not been modeled in the literature. The countercurrent, cocurrent and crossflow configurations (all single dimensional mass transfer cases) for gas separation have been modeled in literature primarily by numerical integration of the differential equations over the relevant boundary conditions. Incorporation of nonlinearities such as pressure and permeability variations complicate the mathematics considerably for a single dimension, and make their solution almost impossible in two dimensions. This paper proposes an algorithm that simplifies the understanding of the problem posed, in terms of practical parameters (such as stage cut), and analyses the three flow patterns (radial crossflow, countercurrent, and cocurrent) in detail.     

Sixth algebraic order trigonometrically fitted predictor–corrector methods for the numerical solution of the radial Schrödinger equation

Our new trigonometrically fitted predictor–corrector (P–C) schemes presented here are based on the well known Adams–Bashforth–Moulton methods: the predictor is based on the fifth order Adams–Bashforth scheme and the corrector on the sixth order Adams–Moulton scheme. We tested the efficiency of our newly developed schemes against well known methods, with excellent results. The numerical experiments showed that at least one of our schemes is noticeably more efficient compared to other methods, some of which are specially designed for this type of problem. It is also worth mentioning that this is the first time that sixth algebraic order trigonometrically fitted Adams–Bashforth–Moulton P–C schemes are used to efficiently solve the radial Schrödinger equation.Active Member of the European Academy of Sciences and Arts     

Generalized Unsöld theorem and radial distribution function for hydrogenic orbitals

A generalization of Unsöld's theorem is derived, giving the sum over bothl andm for products of hydrogenic functions with givenn. A generalized radial distribution functionD _n (r) is introduced and its properties discussed. Asn ,D _n (r) approaches a universal reduced form, for which an empirical representation is given.     

Use of binomial coefficients in fast and accurate calculation of Löwdin-<Emphasis Type="Italic">α</Emphasis> radial functions

In the present paper, we introduce a new algorithm for the development of efficient numerical methods for the analytical solution of the Löwdin-α radial function. The final results are expressed through the binomial coefficients, which enable fast and accurate calculation of the Löwdin-α radial function. The comparisons of the obtained results with the literature have shown that the presented approach can be used for the fast calculation of multicenter multielectron integrals over Slater-type orbitals (STOs). The efficiency of the algorithm is discussed and its performance with several examples is demonstrated.     

New optimized two-derivative Runge-Kutta type methods for solving the radial Schrödinger equation

This paper focuses on adapted two-derivative Runge-Kutta (TDRK) type methods for solving the Schrödinger equation. Two new TDRK methods are derived by nullifying their phase-lags and the first derivatives of the phase-lags. Error analysis is carried out by means of asymptotic expressions of the local errors. Numerical results are reported to show the efficiency and robustness of the new methods in comparison with some RK type methods specially tuned to the integration of the radial time-independent Schrödinger equation with the Woods–Saxon potential.     

A new optimized symmetric 8-step semi-embedded predictor–corrector method for the numerical solution of the radial Schrödinger equation and related orbital problems

In this work we introduce a new predictor–corrector (PC) pair form (SEPCM) for the numerical integration of second-order initial-value problems and a new optimized eight-step symmetric predictor–corrector method with minimal phase-lag and algebraic order ten is constructed. The new method is based on the multistep symmetric method of Quinlan–Tremaine (Astron. J. 100(5):1694–1700, 1990), with eight steps and eighth algebraic order and constructed to solve numerically the radial time-independent Schrödinger equation during the resonance problem with the use of the Woods-Saxon potential. It can also be used to integrate related IVPs with oscillatory solutions such as orbital problems. We compare the new method to some recently constructed optimized methods and other methods from the literature. We measure the efficiency of the methods and conclude that the new optimized method is the most efficient of all the compared methods and for all the problems solved.     

A new two stages tenth algebraic order symmetric six-step method with vanished phase-lag and its first and second derivatives for the solution of the radial Schrödinger equation and related problems

The presentation, development and analysis of a new two-stages tenth algebraic order symmetric six-step method is introduced, for the first time in the literature, in this paper. More specifically, we present the development of the new method (requesting the highest algebraic order and the elimination of the phase-lag and its first and second derivatives), the analysis (error analysis and stability and interval of periodicity analysis) and the evaluation of the new developed method comparing its efficiency with the efficiency of well known methods and very recently produced methods in the literature on the approximate solution of the resonance problem of the one dimensional (or radial) Schrödinger equation. From the developments achieved and the results presented, we prove that the new obtained method is most more effective than other well known or recently developed methods of the literature.     

Study of direction of cyclization of malonodithioamides as a method of investigation of reactivity of α-diazothioacetamides

The reaction of malonothioamides with benzene-sulfonyl azide and 2-azido-3-ethylbenzthiazolium tetrafluoroborate gave amides of 2-diazothiomalonic acid, which underwent cyclization to a mixture of 5-N-R-amino-1,2,3-thiadiazole-4-carbothioamides and 5-amino-1,2,3-thiadiazole-4-N-R-carbothioamides. The ratio of the isomeric thiadiazoles formed in this reaction is the same as in the reactions of 2-diazo-2-cyanoacetamides, 5-amino-1,2,3-thiadiazole- and 5-mercapto-1,2,3-triazole-4-carboxamides with P₄S₁₀ and of 5-amino-1, 2,3-thiadiazole-4-carbonitriles with H₂S; it is characteristic of the influence of substituents on the reactivity of -diazothioacetamides. It was found that the cyclization of the diazo compounds is accelerated when electron-acceptor substituents are attached to the nitrogen atom of the carbothioamide group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1106–1112, August, 1992.     

Synthesis of a Pair of Derivatives of N-Methylpyrrole Polyamide

A pair of derivatives of tetrameric N-methylpyrrole polyamide were synthesized in order to develop a new method for the study of interaction of the polyamide derivatives with DNA. Indole acetic acid and nicotinic acid were introduced to the polyamide in the synthesized compound, which showed an expected red shift in the UV spectrum. These compounds may function as a potential tool in the detection of the polyamide binding to DNA.     

Structure of Potassium of Undecatungstomononickelosilicate

ＳｔｒｕｃｔｕｒｅｏｆＰｏｔａｓｓｉｕｍｏｆＵｎｄｅｃａｔｕｎｇｓｔｏｍｏｎｏｎｉｃｋｅｌｏｓｉｌｉｃａｔｅＱｕＬｕｎ－Ｙｕ；ＭａＲｏｎｇ－Ｈｕａ；ＣｈｅｎＹａ－Ｇｕａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＮｏｒｔｈｅａｓｔＮｏｒｍａｌＵ...     

Analysis of Significance of Unite Examination of AFP and DNA Polymorphism of P3 Promoter of IGF-ⅡGene

The DNA of P3 promoter region of IGF-Ⅱ gene was obtained by means of PCR technique. The examination of DNA polymorphism by restriction endonuclease BstE Ⅱ and the examination of AFP by bioluminescence immunoassay technique were carried out. The results have a significant difference(P<0.005). But the positive rate of AFP is higher than that of DNA polymorphism. The experimental result shows that the change of the DNA polymorphism of IGF-Ⅱis not the only carcinogenic factor. The suggested unite examination is the best method for the diagnosis of the primary hepatocellular carcinoma.     

Synthesis of Related Compounds of Carotenoid

类胡萝卜素是一类奇特的色素，由高等植物和微生物光化学合成，作为防止单线氧通过光敏反应产生危害的必要基团，类胡萝卜素最近受到了关注。类胡萝卜素联于富勒烯上，既可大大增加在可见光区域光诱导电子转移的有效吸收断面，又可抑制富勒烯敏化单线氧的危害能力。合成了类胡萝卜素的相关化合物，报道的某些反应条件先进且简洁。     

Analysis of Significance of Unite Examination of AFP and DNA Polymorphism of P3 Promoter of IGF- Ⅱ Gene

IntroductionTheinnatecharacterofthesolidcarcinomaistheresultthatcellgrowthgetsoutofcontrol.Itsbasicreasonconsistsintheabnormalityofthetumorgene .SomeonethinksthatthegeneofIGF Ⅱisoneofthecancergenesofthe primaryhepatocellularcarcino ma[1] ,andalsothinkstheoverexpressionofthegeneofIGF Ⅱtakesplaceintheearlierperiodofthepri maryhepatocellularcarcinoma ,whichmaybetheear lierdiagnosticnormofprimaryhepatocellularcarcino ma .ThefurtherresearcheshavedemonstratedthattheactivationofIGF Ⅱ genepromo…     

Kinetics of tautomerization of 1,3,4,7-tetramethylisoindole

The kinetics of transformation of 1,3,4,7-tetramethylisoindole(1)to 1,3,4,7-tetramethyl-1H-isoindole(2)in water or in deuterium oxide at various pH or pD at 25℃ were measuredspectrophotometricalty.The results indicated that the transformation of 1 to 2 could be promotedby acid and base.From the solvent isotope effects and the fact that the 1-position of isoindole nucleusis electron-rich,the mechanism of this transformation is suggested.     

Analysis of Chemical Incredients of Angelica Sinnesis——Analysis of Non-Volatile Constituents of Roots

In the present investigation,the non-volatile constituents of Danguei (Tang-Kuei) roots of Gansu origin [Angelica sinensis (Oliv.) Diels] were analyzed and thirty seven organic constituin s were also identified,fifteen of which have not been recorded in literature before,including a new optically active compound named as Angelicide and an antibiotie,Brereldin A.By plasma emission spectrometry,thirteen minor elements were also detecled     

TPSR Studies of the Activation of

TPSR　Studies　of　the　Activation　of　...     

Peculiarities of dissociative ionization of alkylcyclopentadienyl nitrosyl π-complexes of nickel

The decomposition of alkylcyclopentadienyl nitrosyl -complexes of nickel, (C₅H₄R)(NO)Ni (R=H, Et,i-Pr, CH₂Ph), under the action of electron impact has been studied. The nature of the nitrosyl ligand has been shown to be the factor determining the main fragmentation pathway which involves the abstraction of an NO molecule. The effect of the nature of the ligand on the ability of the molecular ion (C₅H₄R)LNi⁺ (L=C₅H₄R, C₅H₅, C₃H₅, NO) to rearrange with hydrogen atom migration from one ligand to another has been considered. The structure of the alkyl group R determines a competing fragmentation pathway involving cleavage of the -C-C bond with respect to the cyclopentadienyl ring in the substituent.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1985–1988, November, 1993.