Improved inorganic ion-exchangers

The possibility of using the sol-gel method for preparation of inorganic ion-exchangers with a silica gel matrix has been demonstrated on the ammonium molybdophosphate-silica gel (AMP-SG) system. For the preparation of the ion-exchanger a sodium silicate solution, containing AMP and components to cause gelling to silica gel after increase of the temperature of the solution, is poured into a hot stirred silicone oil. The solution forms droplets, which are filtered off after their gelling, washed and dried. Beads containing 65 wt.% of AMP per gram of dry material have been prepared by this method and tested in ion-exchange columns for caesium removal from nitric acid solutions. Caesium may easily be desorbed with ammonium chloride or nitrate solutions. The ion-exchanger is suitable for long-time reversible column operation, having not only good chemical, thermal and radiation stabilities but also good mechanical and hydrodynamic properties and resistance to abrasion. It combines the advantage of the good kinetics of ion-exchange obtained with microparticles of precipitated inorganic ion-exchanger, with the low flow resistance of large particles.     

Radiation chemistry of polyethylene. XIV. Allyl radical decay kinetics in different types of polyethylene

The decay kinetics of the chain allyl free radical has been studied in the following morphological forms of polyethylene (PE): Marlex bulk film, hydrogenated PE, and extended-chain PE. Coupled with previous work on single-crystalline PE it can be seen that the decay rate is greater the more amorphous the sample. In the Marlex bulk film and hydrogenated PE the decay can be interpreted in terms of a simultaneous fast and slow decay process by means of our Q-function equation, but with rising temperature the decay approximates a single rate process. With extended-chain PE the allyl decay rate does not become appreciable until the melting range is approached. The fraction of allyl radicals decaying by the slow process is 2 to 10 times greater than the fraction of fast decaying radicals. The ratio of the fast decay rate constant to that of the slow rate constant is greater for the bulk Marlex film than for the hydrogenated PE. All ratios decrease with rising temperature. For times up to about 150 min the allyl decay in the extended-chain PE accurately follows a single second-order decay law with a time-independent diffusion controlled reaction rate constant.     

Atomgewichte

Ohne Zusammenfassung     

Leitf?higkeit und konduktometrische, elektrometrische Titration

Ohne Zusammenfassung     

Measurement of the CP-violation parameter sin2φ1 with a new tagging method at the Υ(5S) resonance

We report a measurement of the CP-violation parameter sin2φ1 at the Υ(5S) resonance using a new tagging method, called "B-π tagging." In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψK(S)(0) CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B-π(+) and B-π(-) tagged J/ψK(S)(0) yields, we determine sin2φ1=0.57±0.58(stat)±0.06(syst). The results are based on 121 fb(-1) of data recorded by the Belle detector at the KEKB e(+)e(-) collider.     

Search for CP violation in τ±→K(S)0π±ντ decays at Belle

We report on a search for CP violation in τ(±)→K(S)(0)π(±)ν(τ) decays using a data sample of 699 fb(-1) collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K(S)(0)π(±) system and found to be compatible with zero with a precision of O(10(-3)) in each mass bin. Limits for the CP violation parameter Im(η(S)) are given at the 90% confidence level. These limits are |Im(η(S))| < 0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.     

Search for CP violation in D± meson decays to ϕπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D(±)→K(+)K(-)π(±) and the Cabibbo-favored decays D(s)(±)→K(+)K(-)π(±) in the K(+)K(-) mass region of the ? resonance. Using 955 fb(-1) of data collected with the Belle detector, we obtain A(CP)(D+→?π+)=(+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5. We find no evidence for direct CP violation.     

Effect of substitution of Ce on superconducting properties of Bi1.7Pb0.3Sr2Ca2−x Ce x Cu3O10+δ system

We have investigated the superconducting properties of the Bi_1.7 Pb_0.3Sr₂Ca_2−xCe _x Cu₃O_10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T _c (2 : 2 : 2 : 3) phase decreases and low T _c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent state in this system; that is, Ca²⁺ → Ce⁴⁺ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T _c of the system.     

Analysis of cytokinin nucleotides by capillary zone electrophoresis with diode array and mass spectrometric detection in a recombinant enzyme in vitro reaction

A capillary zone electrophoresis (CZE) method for separation of adenosine and N⁶-isopentenyladenosine (cytokinin) nucleotides was developed, optimized and validated. Aqueous solutions of several amino acids were evaluated as the background electrolyte constituents. Separation of six nucleotides in less than 20 min with high theoretical plate number (up to 400 000 for isopentenyladenosine triphosphate) was achieved using a 100 mM sarcosine/ammonia buffer at pH 10.0. The detection limits of the CZE-UV method are in the low micromolar range (0.69–1.27 μmol L⁻¹). Good repeatability of migration times (within 1.3%), peak areas (within 1.8%) and linearity (R² > 0.999) was achieved over the concentration range 5–1000 μmol L⁻¹. The method was used to assay the activity of the recombinant Arabidopsis thaliana isopentenyltransferase 1 (AtIPT1). Baseline separation of isopentenylated nucleotides by CE–ESI-MS using a volatile buffer (30 mM ammonium formate; pH 10.0) was accomplished. The identities of the reaction products – isopentenyladenosine di- and triphosphate were confirmed by HPLC-QqTOF-MS. Dephosphorylation of ATP was observed as a parallel reaction.     

Promoting Percent as a Proportion in Eighth‐Grade Mathematics

The literature provides many and varied suggestions for promoting conceptual understanding of percent and performing percent calculations. The diversity of ideas provides a wide selection but offers little clarity on the true nature of percent. From the premise that percent is fundamentally a proportion, this study incorporated a proportional approach for percent problem solving within an instructional program on percent. Classroom research with eighth‐grade students indicated that the method was readily adopted by students and helped them experience success in percent problem solving, with percent problem solving proficiency maintained over a delayed period. It is hypothesized that the method has the potential to promote students' conceptual knowledge of percent as a proportion and the multiplicative structure of percent, as well as to build proportional knowledge.