Cytotoxic and NF-κB inhibitory sesquiterpene lactones from Piptocoma rufescens

Six new (1-6) and eight known germacranolide-type sesquiterpene lactones, along with several known phenylpropanol coumarates and methylated flavonoids, were isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. The new compounds were identified by analysis of their spectroscopic data, with the molecular structure of 3 being established by single-crystal X-ray diffraction. The absolute configurations of the sesquiterpene lactones isolated were determined from their CD and NOESY NMR spectra, together with the analysis of Mosher ester reactions. Bioassay screening results showed the majority of the sesquiterpene lactones isolated (1-13) to be highly cytotoxic toward the HT-29 human colon cancer cell line, with the most potent compound being 15-deoxygoyazensolide (10, IC(50), 0.26 μM). In addition, several of the sesquiterpene lactones exhibited NF-κB (p65) inhibitory activity.     

Portable capillary liquid chromatography for pharmaceutical and illicit drug analysis

A newly developed portable capillary liquid chromatograph was investigated for the separation of various pharmaceutical and illicit drug compounds. The system consists of two high‐pressure syringe pumps capable of delivering capillary‐scale flow rates at pressures up to 10 000 psi. Capillary liquid chromatography columns packed with sub‐2 μm particles are housed in cartridges that can be inserted into the system and easily connected through high‐pressure fluidic contact points by simply applying a specific, predetermined torque rather than using standard fittings and less precise sealing protocols. Several over‐the‐counter analgesic drug separations are demonstrated, along with a simple online measurement of tablet dissolution. Twenty illicit drug compounds were also separated across six targeted drug panels. The results described in this study demonstrate the capability of this compact liquid chromatography instrument to address several important drug‐related applications while simplifying system operation, and greatly reducing solvent usage and waste generation essential for onsite analysis.     

Bilinear electric field gradient focusing

Electric field gradient focusing (EFGF) uses an electric field gradient and a hydrodynamic counter flow to simultaneously separate and focus charged analytes in a channel. Previously, most EFGF devices were designed to form a linear field gradient in the channel. However, the peak capacity obtained using a linear gradient is not much better than what can be obtained using conventional CE. Dynamic improvement of peak capacity in EFGF can be achieved by using a nonlinear gradient. Numerical simulation results indicate that the peak capacity in a 4-cm long channel can be increased from 20 to 150 when changing from a linear to convex bilinear gradient. To demonstrate the increased capacity experimentally, an EFGF device with convex bilinear gradient was fabricated from poly(ethylene glycol) (PEG)-functionalized acrylic copolymers. The desired gradient profile was confirmed by measuring the focusing positions of a standard protein for different counter flow rates at constant voltage. Dynamically controlled elution of analytes was demonstrated using a monolith-filled bilinear EFGF channel. By increasing the flow rate, stacked proteins that were ordered but not resolved after focusing in the steep gradient segment were moved into the shallow gradient segment, where the analyte peak resolution increased significantly. In this way, the nonlinear field gradient was used to realize a dynamic increase in the peak capacity of the EFGF method.     

An efficient evolutionary multi-objective framework for MEMS design optimisation: validation, comparison and analysis

The application of multi objective evolutionary algorithms (MOEA) in the design optimisation of microelectromechanical systems (MEMS) is of particular interest in this research. MOEA is a class of soft computing techniques of biologically inspired stochastic algorithms, which have proved to outperform their conventional counterparts in many design optimisation tasks. MEMS designers can utilise a variety of multi-disciplinary design tools that explore a complex design search space, however, still follow the traditional trial and error approaches. The paper proposes a novel framework, which couples both modelling and analysis tools to the most referenced MOEAs (NSGA-II and MOGA-II). The framework is validated and evaluated through a number of case studies of increasing complexity. The research presented in this paper unprecedentedly attempts to compare the performances of the mentioned algorithms in the application domain. The comparative study shows significant insights into the behaviour of both of the algorithms in the design optimisation of MEMS. The paper provides extended discussions and analysis of the results showing, overall, that MOGA-II outperforms NSGA-II, for the selected case studies.     

A cytotoxic dimeric furanoheliangolide from Piptocoma rufescens

A new sesquiterpene lactone, rufescenolide C (1), the first furanoheliangolide dimer, was isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. Its structure was determined by interpretation of its spectroscopic data, with the absolute configuration being established by analysis of the CD spectrum. A plausible biogenesis of this dimer is proposed. This compound showed potent cytotoxicity with an IC₅₀ value of 150 nM, when tested against HT-29 human colon cancer cells.     

One-Pot Oxidation and Nitrosation of β-Alkanolamines with KMnNO4-NaNO2. A Convenient Preparation of β-Ketonitrosamines

The oxidation and nitrosation of β-alkanolamines to the corresponding β-ketonitrosamines is reported. The oxidation is carried out with potassium permanganate in acidic medium, followed by nitrosation of the protonated aminoketone, with sodium nitrite, to the corresponding β-ketonitrosamine.     

Energy transport in the inductively coupled plasma

Time- and space-resolved electron density measurements, made both above the load coil and in the load coil region of a pulsed inductively coupled plasma, are presented. These data, coupled with argon and calcium emission data, give values for the rates of both radial and vertical transport in the plasma. The data indicate that analyte emission behavior is governed primarily by the rate at which the central channel can be heated through radial transport processes. The electron densities measured in the load coil region agree well with electron densities calculated by models assuming local thermodynamic equilibrium, but agree poorly with non-equilibrium models. Some of the timedependent emission behavior observed in previous work with modulated plasmas is explained by non-uniform heating of argon in the load coil region.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Interaction of oxygen, carbon monoxide and nitrogen with (001) and (110) faces of molybdenum

A combination of low-energy electron diffraction and retarding potential measurements was employed to study gaseous adsorption on atomically clean (001) and (110) Mo single crystal surfaces. Adsorption of oxygen on the (001) surface at room temperature occurred with a sticking coefficient close to unity and produced a large increase in work function and appreciable changes in the intensity distributions of the integral order diffraction beams, without the appearance of any new diffraction beams. These results indicate that a surface monolayer of oxygen was formed with a unit mesh having the same dimensions as that of the underlying molybdenum surface. Exposures above 6 × 10⁻³ Torr-sec produced a uniform decrease in intensities, thus indicating a second monolayer with amorphous structure. On heating, two additional surface structures were observed, characterized by one-half and one-third order beams, respectively. A clean surface was obtained by heating above 1100 °C. An exposure of 1 to 7 × 10⁻⁷ Torr-sec of oxygen for the (110) face resulted in two types of patterns characteristic of lattices with one-quarter and one-half the surface density of the (110) Mo face, with an increased work function accompanying the latter pattern. Exposure of the clean surface at 400 to 800 °C produced similar patterns of enhanced intensities with no increase in work function. Possible models are discussed. It is concluded that place exchange models account for these results, as well as the one-half and one-third order structures on the (001) face, in a more satisfactory manner than adsorption above the surface. An exposure to 10⁻⁵ Torr-sec produced a monolayer coverage with a unit mesh similar to that of the molybdenum substrate. Additional exposure resulted in further amorphous adsorption. Adsorption of CO produced changes in the intensity distributions, with the appearance of no new maxima, for both (001) and (110) Mo surfaces. Nitrogen, at an exposure of 3 × 10⁻³ Torr-min did not adsorb on either the (001) or (110) Mo surface, but when dissociated by electron impact it adsorbed on both Mo surfaces with the same dimensions of unit mesh as those of the Mo substrates and with an increase in work function of 1.05 eV for the (001) and 0.05 eV for the (110) surface.