Influence of surfactants in aqueous-based polymeric dispersions on the thermomechanical and adhesive properties of acrylic films

Good adhesion between a polymeric film and the surface of a solid substrate is critical to the performance of coated pharmaceutical products. Previous research has shown that tablet wettability by an organic-based cellulosic solution could predict the extent of film-tablet adhesion. Using an aqueous-based acrylic polymeric dispersion, the current study investigated the relationship between film adhesion and tablet wettability. Up to 10% (w/w based on dry polymer weight) polysorbate 80 or sorbitan monooleate was incorporated into the film-coating formulations. While the contact angle between the polymeric dispersion and the tablet surface was dependent on the type and concentration of surfactants added to the coating formulation, no correlation between tablet wettability and polymer adhesion could be established. The addition of surfactants to formulations containing the hydrophobic plasticizer tributyl citrate (TBC) caused lowering of the glass transition temperature of the polymer. Increased force of adhesion, elongation at adhesive failure, and adhesive toughness, however, were noted only in the TBC-plasticized films containing polysorbate 80. These findings demonstrate that our understanding of the mechanisms involved in film-tablet adhesion is still quite limited.     

无卤阻燃PC/ABS的制备及燃烧性能

以齐聚磷酸酯(BDP)作为添加型阻燃剂制备了阻燃PC/ABS塑料合金,采用锥形量热仪(CONE)、扫描电镜(SEM)及热裂解-气相/质谱法(Py-GC/MS)等对材料的燃烧性能和阻燃机理进行了研究.结果表明,阻燃剂BDP对PC/ABS有良好的阻燃效果;BDP的加入使PC/ABS燃烧残留物上产生大量的致密微孔,同时由Py-GC/MS分析表明BDP的加入降低了PC/ABS可燃性降解产物的生成,裂解产物中含有三苯基磷酸酯(TPP),说明BDP在塑料合金降解过程中分解生成TPP发挥阻燃作用.     

A rapid technique to evaluate the oxidative stability of a model drug

The objective of the current study was to investigate the oxidative induction time (OIT) as a measurement of the stability of an oxygen-sensitive model drug. The OIT was determined by differential scanning calorimetry and represents the time required for oxidative decomposition to occur at a given temperature. Samples were heated to a specific temperature under a nitrogen blanket then held isothermal while exposed to oxygen. The experiment proceeded until oxidative degradation of the sample was apparent from the real-time heat flow graphs. Variables investigated in this study included different lots and suppliers of a model drug as well as the addition of antioxidants. Results demonstrated that the stability of the drug was dependent on the supplier. All antioxidants investigated in this study improved oxygen stability of the model compound, as evidenced by a longer OIT. Butylated hydroxyanisole (BHA) was found to better stabilize the drug than butylated hydroxytoluene at equivalent concentrations. The combination of ascorbic acid and BHA provided the greatest protection against oxidation of the model compound. The results of this study demonstrate the usefulness of OIT to investigate the oxygen stability of pharmaceutical compounds.     

A DEFORMATION STUDY OF COBALT OXIDE-ALUMINA-SILICA MIXTURES1

A deformation study of CoO-Al₂O₃-SiO₂ mixtures was made to determine the fluxing effect of cobalt in such silicate mixtures as glazes and enamels. The deformation eutectics for cobalt and alumina, cobalt and silica, and cobalt-alumina-silica were determined and isothermal diagrams drawn.     

Special Issues in Honor of Professor Dr. Dr. hc mult. Wittko Francke, 28 November 1940–27 December 2020

Journal of Chemical Ecology -     

Alteration of Ca2+ fluxes in brain microsomes by K+ and Na+: modulation by sulfated polysaccharides and trifluoperazine

Rat brain microsomes accumulate Ca2+ at the expense of ATP hydrolysis. The rate of transport is not modulated by the monovalent cations K+, Na+, or Li+. Both the Ca2+ uptake and the Ca(2+)-dependent ATPase activity of microsomes are inhibited by the sulfated polysaccharides heparin, fucosylated chondroitin sulfate, and dextran sulfate. Half-maximal inhibition is observed with sulfated polysaccharide concentrations ranging from 0.5 to 8.0 micrograms/ml. The inhibition is antagonized by KCl and NaCl but not by LiCl. As a result, Ca2+ transport by the native vesicles, which in the absence of polysaccharides is not modulated by monovalent cations, becomes highly sensitive to these ions. Trifluoperazine has a dual effect on the Ca2+ pump of brain microsomes. At low concentrations (20-80 microM) it stimulates the rate of Ca2+ influx, and at concentrations > 100 microM if inhibits both the Ca2+ uptake and the ATPase activity. The activation observed at low trifluoperazine concentrations is specific for the brain Ca(2+)-ATPase; for the Ca(2+)-ATPases found in blood platelets and in the sarcoplasmic reticulum of skeletal muscle, trifluoperazine causes only a concentration-dependent inhibition of Ca2+ uptake. Passive Ca2+ efflux from brain microsomes preloaded with Ca2+ is increased by trifluoperazine (50-150 microM), and this effect is potentiated by heparin (10 micrograms/ml), even in the presence of KCl. It is proposed that the Ca(2+)-ATPase isoforms from brain microsomes is modulated differently by polysaccharides and trifluoperazine when compared with skeletal muscle and platelet isoforms.     

Do Foliar Phenolics Provide Protection to Heliothis virescens from a Baculovirus?

The effects of chlorogenic acid on larval survival and growth of the tobacco budworm Heliothis virescens and larval susceptibility to Helicoverpa zea nucleopolyhedrovirus (HzSNPV) were studied with an artificial diet and transgenic tobacco Nicotiana tabacum. Survival of neonates on over- or underexpressed phenylalanine ammonia-lyase (PAL) transgenic tobacco lines was positively correlated with the level of chlorogenic acid. Larval weight was not correlated with the level of chlorogenic acid in tobacco foliage. On the other hand, larval weights on artificial diet supplemented with chlorogenic acid were negatively correlated with chlorogenic acid concentration. Second instars treated on virus-treated (10 occlusion bodies/larva) tobacco leaf disks for 24 hr and then reared on tobacco leaves showed higher survival time and increased mortality on lines with increasing levels of chlorogenic acid. However, viral-related larval mortality on artificial diet was negatively correlated with dietary chlorogenic acid. These results illustrate the inadequacy of artificial diet studies in establishing causal relationships among plant chemistry, herbivores, and natural enemies.     

Integrin alphavbeta5 participates in the binding of photoreceptor rod outer segments during phagocytosis by cultured human retinal pigment epithelium

Because glycolysis is thought to be important for maintenance of cellular ion homeostasis, the aim of the present study was to examine the role of glycolysis in the control of cytosolic calcium ([Ca2+]i) and cell shortening during conditions of increased calcium influx. Thus, [Ca2+]i and unloaded cell shortening were measured in fura-2/AM loaded rat ventricular myocytes. All cells were superfused with Tyrode's solution containing glucose and pyruvate (to preserve oxidative metabolism), and glycolysis was inhibited by iodoacetate (IAA, 100 microM). Calcium influx was increased, secondary to an increase in intracellular sodium, by addition of veratrine (1 microgram/ml), or directly by either elevating [Ca2+]o from 2 to 5 mM or by exposing the cells to isoproterenol (1 to 100 nm). Veratrine exposure caused a time-dependent increase in both diastolic and systolic [Ca2+]i that resulted in cellular calcium overload and hypercontraction. The rate of increase in [Ca2+]i was more rapid in IAA-treated than in untreated myocytes, leading to a 13+/-3 v 5+/-2% increase (P<0.05) in diastolic [Ca2+]i after 5 min of exposure. The corresponding increases in systolic [Ca2+]i were 43+/-6 and 24+/-5% (P<0.05). Elevated [Ca2+]o resulted in increased [Ca2+]i transient amplitudes and cell shortening. These responses were each attenuated by inhibiting glycolysis, so that the increase was 38+/-5 v 68+/-9% ([Ca2+]i transient amplitude, P<0.05) and 41+/-11 v 91+/-18% (cell shortening, P<0.05). Inhibition of glycolysis did not, however, affect the increase in calcium transient or cell shortening during addition of isoproterenol. We conclude that glycolysis plays an essential role in the maintenance of intracellular calcium homeostasis during severe calcium overload. Glycolysis was also essential for signalling the inotropic effect that accompanied elevation in extracellular calcium, while the changes in intracellular calcium following administration of isoproterenol were not influenced by glycolysis in the present model.