Rheological and Aging Properties of Composite Modified Bitumen by Styrene–Butadiene–Styrene and Desulfurized Crumb Rubber

Taking advantage of crumb rubber from waste tires to modify bitumen is widely for the environmentally friendly and sustainable development of pavement. This study investigated the modification mechanism, rheological, and aging properties of styrene–butadiene–styrene (SBS)/desulfurized crumb rubber (DCR) composite modified bitumen (SBS/DCRMB). Morphological features and chemical characteristics were assessed by fluorescence intensity measurement and gel permeation chromatography (GPC), respectively, and results demonstrated that the DCR and SBS modifier in SBS/DCRMB had been vulcanized and formed a three-dimensional network structure. Moreover, a comparison of the GPC elution curve showed the residual bitumen hardly changed due to carbon black released from DCR of SBS/DCRMB during the aging process of SBS/DCRMB, and the polymer molecules condensed to larger units. However, the remaining bitumen in SBSMB had changed evidently and the polymer degraded to smaller molecules. Meanwhile the rheological testing results, including multiple stress creep recovery, linear amplitude sweep and bending beam rheometer, declared that the SBS/DCRMB is superior to SBSMB before and after aging.

TRACE LEVEL DETERMINATION AND QUANTIFICATION OF POTENTIAL GENOTOXIC IMPURITIES IN DASATINIB DRUG SUBSTANCE BY UHPLC/INFINITY LC

<p class="Default"><strong>Objective: </strong>A simple, cost-effective and mass compatible ultra-high fast performance liquid chromatographic (Agilent-Infinity LC 1290) method has been developed and validated for the determination of potentially genotoxic impurities in dasatinib active pharmaceutical ingredients.</p><p class="Default"><strong>Methods: </strong>This method comprises the determination of three possible genotoxic impurities in dasatinib. The mobile phase is trifluoroacetic acid, acetonitrile and water with linear gradient elution curve number 6. The column used for the development and validation is zorbax RRHD eclipse plus C18 with the length of 50 mm, the internal diameter of 2.1 mm and particle size of 1.8 microns.</p><p class="Default"><strong>Results: </strong>The limit of detection of the potential genotoxic impurities are less than 0.1 µg/ml with respect to dasatinib test concentration of 1000 µg/ml. The limit of quantification of the potential genotoxic impurities is less than 0.3 µg/ml with respect to dasatinib test concentration of 1000 µg/ml.</p><p style="margin: 6pt 0cm; text-align: justify;"><strong>Conclusion: </strong>This method has been validated as per ICH guidelines Q2 (R1). These three potential mutagenic impurities are not degradant impurities of dasatinib and its only process related impurities. The method development has been approached using the QbD principle.</p>

New Progress of Plate Model of Chromatogram: Five Distinct Plate Numbers

The five plate numbers were peak plate number (q’), slip-mechanism plate number (q), theoretical plate number (n0), real plate number (n) and plate-model plate number (q0). Slip mechanism was introduced into plate model and then a new equation of elution curve was deduced. The relational expression of five plate numbers was deduced through the new equation. Peak plate number and slip-mechanism plate number were new plate numbers derived from slip mechanism, and the physical pictures of them was discussed. Peak plate number would be regarded as an asymmetry index of peak, as column plate number is regarded as an efficiency index of column.

Isotope production for medical usage using fast neutron reactions

99Mo was produced by the 100Mo(n,2n)99Mo reaction using 14-MeV neutrons from the D(3H,n)4He reaction at Fusion Neutronics Source Facility (FNS) at JAEA. A target of titanium oxide gel with molybdenum oxide was irradiated and used as the 99mTc/99Mo generator. The growth curve of 99mTc in the titanium gel target and the elution curve of 99mTc from the 99Mo/99mTc generator were obtained.

Determination of Diffusion Coefficients of Selected Long Chain Hydrocarbons using Reversed- Flow Gas Chromatographic Technique

The reversed-flow gas chromatography (RF-GC) technique was used to study the evaporation rate and estimating the diffusion coefficient of samples. The RF-GC system comprises of six-port valve, sampling and diffusion column, detector and modified commercial gas chromatography machine. Selected long chain of hydrocarbons (99.99% purity) was used as samples. The solute (stationary phase) were carried out by carrier gas (mobile phase) to the detector. The data obtained from the RF-GC analysis were analysed by deriving the elution curve of the sample peaks using mathematical expression to find the diffusion coefficients values of respective liquids. The values obtained were compared with theoretical values to ensure the accuracy of readings. The interesting findings of the research showed the theoretical values of equilibrium at liquid-gas interphase lead to profound an agreement with the experimental evidence, which contributes for the references of future studies.