55 research outputs found

    Predicting Crystallization of Amorphous Drugs with Terahertz Spectroscopy.

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    There is a controversy about the extent to which the primary and secondary dielectric relaxations influence the crystallization of amorphous organic compounds below the glass transition temperature. Recent studies also point to the importance of fast molecular dynamics on picosecond-to-nanosecond time scales with respect to the glass stability. In the present study we provide terahertz spectroscopy evidence on the crystallization of amorphous naproxen well below its glass transition temperature and confirm the direct role of Johari-Goldstein (JG) secondary relaxation as a facilitator of the crystallization. We determine the onset temperature Tβ above which the JG relaxation contributes to the fast molecular dynamics and analytically quantify the level of this contribution. We then show there is a strong correlation between the increase in the fast molecular dynamics and onset of crystallization in several chosen amorphous drugs. We believe that this technique has immediate applications to quantify the stability of amorphous drug materials.JS and JAZ would like to acknowledge the UK Engineering and Physical Sciences Research Council for funding (EP/J007803/1).This is the final version of the article. It first appeared from ACS at http://dx.doi.org/10.1021/acs.molpharmaceut.5b0033

    Pharmaceutical Particle Engineering via Spray Drying

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    Measurement of the Stress State in the Lower Link of the Three-Point Hitch Mechanism

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    Agricultural machines and their implements are subjected to dynamic loads during farm operations. Depending on the type of operation (e.g. lifting or plowing), lower links of the three-point hitch mechanism are exposed to stresses caused by combination of bending moments and axial forces. In this paper we analyzed influence of the soil resistance during plowing in the lower link and the possibility of its failure. The stresses were measured using strain gauges at locations with uniform stress distribution in order to enable more reliable comparison with finite element analysis (FEA). Recorded stresses vs. time were used for identifying mean stresses and amplitudes for different plowing depth and different tractor speeds. Due to the geometry of the lower links and their joints in the three-point hitch mechanism, during plowing and transferring soil resistance, links are loaded not only by axial forces but also by bending moment in the horizontal plane. Under some assumptions, FEA provided us to make relations between the measured stresses and the loads that caused them. Measured stresses show that links have significant safety margin relative to tractor installed power and soil resistance, which enables the possibility of their design optimization. Obtained results may also serve for further analyses of fatigue life prediction, measurement of the draft forces etc

    Severe lung injury following inhalation of nitric acid fumes

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    Objective: We present a rare case of survival following inhalation of nitric acid fumes and its decomposition products, which resulted in severe pulmonary edema and Acute Respiratory Distress Syndrome (ARDS). Successful outcome followed ventilatory support and use of steroids. Design: Case report. Setting: Tertiary-level medical intensive care unit. Patient: A single case of inhalation of nitric oxide fumes. Intervention: Ventilatory support and addition of steroids. Measurement and main results: Improvement and discharge. Conclusion: Inhalation of nitric acid fumes and its decomposition gases such as nitrogen dioxide results in delayed onset of severe pulmonary edema deteriorating into ARDS. Intensive respiratory management, ventilatory support, and steroids can help in survival

    Synthesis and characterization of copper(II) complexes of 4-alkyl/aryl-1,2-naphthoquinones thiosemicarbazones derivatives as potent DNA cleaving agents

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    Copper (II) complexes of some alkyl/aryl-1,2 naphthoquinones thiosemicarbazone have been prepared and characterized. The crystal structure determined for one of the free ligands viz. 4-Pyrrolidine-1-yl-[1, 2] naphthaquinone thiosemicarbazone (5) indicates it to crystallize in the “E’ conformation which is supported by the NMR data. The ligands and copper complexes were evaluated for their DNA cleaving activities in case of circular double stranded plasmid DNA pBR322 under aerobic conditions. Amongst the ligands, compound 8 shows almost quantitative conversion to the linearized DNA in presence of H2O2 oxidant. All copper conjugates show more pronounced interaction with DNA while compounds 3 and 7 are able to yield linearized DNA in presence of the oxidant
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