Kinetic and thermodynamic studies on the adsorption behavior of Rhodamine B dye on Duolite C-20 resin

The adsorption behavior of Rhodamine B dye from aqueous solutions was investigated onto the cation-exchange resin, Duolite C-20 (hydrogen form). The effects of various experimental factors; sorbent amount, contact time, dye concentration and temperature, were studied by using the batch technique. Lagergren pseudo-first-order equation shows good applicability with high correlation coefficients for all ranges of initial dye concentrations and at different temperatures. This equation was used to describe the kinetics of the dye adsorption process. The adsorption constants were evaluated by using both the Langmuir and Freundlich adsorption isotherm models. Thermodynamic parameters were obtained and it was found that the adsorption of Rhodamine B dye onto Duolite C-20 resin was an endothermic and spontaneous process at the temperatures under investigation.     

(3S,4S)-4-氨基-3-羟基-6-甲基庚酸的合成

价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得(S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得(S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。     

Melham's Conjecture on Odd Power Sums of Fibonacci Numbers

Ozeki and Prodinger showed that the odd power sum of the first several consecutive Fibonacci numbers of even order is equal to a polynomial evaluated at a certain Fibonacci number of odd order. We prove that this polynomial and its derivative both vanish at 1, and will be an integer polynomial after multiplying it by a product of the first consecutive Lucas numbers of odd order. This presents an a?rmative answer to a conjecture of Melham.     

Synthesis of Galactosylhydroxylysine and its Analogs

Synthesis of (--)-galactosylhydroxylysine (GHL, I), and its analogs (+)-2 and (+)-3, which are essential for development of assays for osteoporosis, is described starting from (2S,5R)-(+)-hydroxylysine (4).     

A non-metric perfectly normal hereditarily indecomposable continuum

We construct an example of a non-metric perfectly normal hereditarily indecomposable continuum. The example is constructed as an inverse limit of non-metric analogues of solenoids. Theorems needed to insure perfect normality are stated and proven. It is shown that the example cannot be embedded in a countable product of Hausdorff arcs.     

Partial Synthesis of Coenzyme B12 from Cobyric Acid

Here we report the direct chemical synthesis of coenzyme B₁₂ (AdoCbl) from Co_β ‐5′‐deoxyadenosylcobyric acid (AdoCby) and the preparation of the latter from crystalline CN ,H₂O‐cobyric acid (CN ,H₂OC by). AdoCby is a suggested common key intermediate in the biosynthesis of AdoCbl and of other cobamides in microorganisms. AdoCby was thoroughly characterized by spectroscopic means, including homo‐nuclear and hetero‐nuclear NMR , as such data are not available in published work. AdoCbl was prepared from AdoCby in one‐step in over 85% yield, by covalent attachment in aqueous solution of the integral B₁₂‐nucleotide moiety using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC ·HC l) and N‐hydroxybenzotriazole (HOB t) as coupling reagents. By the same procedure crystalline vitamin B₁₂ (CNC bl) was also prepared in 92% yield from CN ,H₂OC by. Coordination of the B₁₂‐nucleotide base at the Co_α ‐face of AdoCby or of CN ,H₂OC by was indicated to assist in the efficient covalent coupling at the activated f‐side chain function to furnish the complete corrinoids AdoCbl and CNC bl.     

A Disposable Homemade Screen Printed Electrochemical Sensor for Vitamin B1 Determination in Multivitamin Ampoules: Potentiometric and Surface Morphology Studies

Thiamine chloride hydrochloride (TCH) is one of the B‐complex vitamins which resemble a very biologically important group of biomolecules. The first screen‐printed graphite ion‐selective sensor for the determination of TCH was prepared and characterized. The sensor is based on TCH‐tetraphenylborate as electrode material. A number of parameters such as the type of solvent mediator, weight percent of the ion‐exchanger, test solution temperature and possible interferences were extensively studied. Moreover, the surface morphology of the prepared sensor was studied using scanning electron microscopy. The sensor shows a Nernstian slope of 30.60±0.07 mV/decade, a low LOD of 5.08×10⁻⁶ mol/L and a wide applicability range of 5.96×10⁻⁶‐1.00×10⁻² mol/L. The sensing graphite ink remains usable for at least one month. Fast potentiometric response was obtained within 5 s and remains stable for at least 60 s. The sensor was applied to the analysis of TCH in pure solutions and multivitamin ampoules from the Egyptian market using the standard addition method and high recovery values of 97–102 % were obtained. Low %RSD values (0.27‐1.30) indicate high precision of the proposed sensor. Our sensor provides the advantages of disposability, simple preparation procedures, sensitivity and easy storage and transportation.     

Extremal solutions for stochastic equations indexed by negative integers and taking values in compact groups

Stochastic equations indexed by negative integers and taking values in compact groups are studied. Extremal solutions of the equations are characterized in terms of infinite products of independent random variables. This result is applied to characterize several properties of the set of all solutions in terms of the law of the driving noise.