MALDI-FTICR imaging mass spectrometry of drugs and metabolites in tissue

A new approach is described for imaging mass spectrometry analysis of drugs and metabolites in tissue using matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR). The technique utilizes the high resolving power to produce images from thousands of ions measured during a single mass spectrometry (MS)-mode experiment. Accurate mass measurement provides molecular specificity for the ion images on the basis of elemental composition. Final structural confirmation of the targeted compound is made from accurate mass fragment ions generated in an external quadrupole-collision cell. The ability to image many small molecules in a single measurement with high specificity is a significant improvement over existing MS/MS based technologies. Example images are shown for olanzapine in kidney and liver and imatinib in glioma.     

A microchip electrophoresis device with integrated electrochemical detection: a direct comparison of constant potential amperometry and sinusoidal voltammetry

A microchip electrophoresis system with integrated electrochemical detection is described in this work. The hybrid device utilizes poly(dimethylsiloxane) as the electrophoresis channel substrate and a planar gold electrode lithographically fabricated onto a glass slide for electrochemical detection. The system is characterized by the separation and detection of various neurotransmitters. The gold working electrode is placed just inside the separation channel without adverse effects on the detection sensitivity, due to the electrical decoupling of the detection and electrophoresis systems. The close proximity of the working electrode to the exit of the separation channel results in symmetric peak shapes and efficient separations (50,000-100,000 plates/m). A direct comparison between the frequency-based electrochemical technique, sinusoidal voltammetry, and the more commonly used constant potential (DC) amperometry is made. Sinusoidal voltammetry is found to be roughly an order of magnitude more sensitive than DC amperometry, with calculated mass detection limits (S/N = 3) of 12 amol and 15 amol for dopamine and isoproterenol, respectively.     

Scanning electrochemical microscopy of model neurons: imaging and real-time detection of morphological changes

Living PC12 cells, a model cell type for studying neuronal function, were imaged using the negative feedback mode of a scanning electrochemical microscope (SECM). Six biocompatible redox mediators were successfully identified from a large pool of candidates and were then used for imaging PC12 cells before and after exposure to nerve growth factor (NGF). When exposed to NGF, cells differentiate into a neuron phenotype by growing narrow neurites (1-2 microm wide) that can extend > 100 microm from the cell proper. We demonstrate that carbon fiber electrodes with reduced tip diameters can be used for imaging both the cell proper and these neurites. Regions of decreased current, possibly resulting from raised features not identifiable by light microscopy, are clearly evident in the SECM images. Changes in the morphology of undifferentiated PC12 cells could be detected in real time with the SECM. After exposure to hypotonic and hypertonic solutions, reversible changes in cell height of <2 microm were measured.     

Production and characterization of pyrolytic oils by pyrolysis of waste machinery oil

The main objective of this work is to propose an alternative method for evaluation of the waste machinery oil which is an environmental problem in Turkey. For this purpose, pyrolysis of waste machinery oil was conducted in a tubular reactor. Effect of the experimental conditions (various temperatures, catalyst type) on the formation of pyrolytic oil, gas, and char was investigated. Nickel supported on silica and zeolite (HZSM-5) were used as catalysts. Properties of the pyrolytic oils were characterized by gas chromatograph equipped with a mass selective detector (GC–MS), gas chromatography with flame ionization detector (GC–FID for boiling point range distribution), nuclear magnetic resonance (¹H NMR) spectroscopy, higher heating value measurement, and elemental analysis. The behavior of the metals in the waste machinery oil and the pyrolytic oil samples was also quantitatively detected by inductively coupled plasma (ICP) analysis. As, Cd and Cr contents of the all pyrolytic oils were found as <0.05 ppm, while Cu content of the pyrolytic oils varied between 0.3 ppm and 0.61 ppm. Only Vanadium contents of the pyrolytic oils obtained at 800 °C (0.342 ppm) and in the presence of HZSM5 (0.57 ppm) increased compared to that obtained by waste machinery oil (0.1 ppm). Lower metal contents of the pyrolytic oils reveal that pyrolysis of the waste machinery oils leads to the formation of environmental friendly pyrolytic oils with higher heating values.     

Ultrabright PbSe magic-sized clusters

We present the synthesis and characterization of novel, ultrasmall PbSe magic-sized nanoclusters (MSCs). Unlike the syntheses of high-quality semiconductor nanoparticles, the MSC synthesis is straightforward, occurring at room temperature in air over several hours. MSCs have core diameters <2 nm and fluoresce in the near-infrared (900 nm) with remarkable quantum efficiencies consistently greater than 50%. The relatively slow growth of MSCs allows for a significant scale up of reaction volumes. Transfer to aqueous solvents has also been demonstrated, establishing MSCs as a potential new fluorophore for applications in biological imaging.     

Mixture design applied to optimize a directly compressible powder produced via cospray drying

Coprocessing via spray drying was applied to improve the compactability of acetaminophen and to select an optimal formulation. Four-component mixtures containing acetaminophen, mannitol, erythritol, and maltodextrin were produced by cospray drying. A D-optimal mixture design was constructed to evaluate the spray dried powder and tablet properties. An increasing mannitol and erythritol content improved powder flowability and density. However, a higher erythritol concentration in the spray dried powder mixture had a negative influence on tablet tensile strength and friability. A higher maltodextrin content increased tablet tensile strength and improved tablet friability, while disintegration time, average particle size, powder flowability, density, and hygroscopicity were negatively influenced.     

Vortex formation and dissolution in sheared sands

Using digital image correlation, we track the displacement fluctuations within a persistent shear band in a dense sand specimen bounded by glass walls undergoing plane strain compression. The data evidences a clear, systematic, temporally recurring pattern of vortex formation, dissolution, and reformation throughout macroscopic softening and critical state regimes. During softening, locally affine deformation zones are observed at various locations along the shear band, which we argue to be kinematic signatures of semi-stable force chains. Force chain collapse then occurs, inducing vortex formation. Local jamming at the conflux of opposing displacements between adjacent vortices arrests the vortices, providing an avenue for potential new force chains to form amidst these jammed regions. The process repeats itself temporally throughout the critical state. The pattern further correlates with fluctuations in macroscopic shear stress. We characterize the nature of the observed vortices, as they are different in our sands comprised of irregular shaped particles, as compared to previous observations from experiments and numerical simulations which involved circular or rounded particles. The results provide an interesting benchmark for behavior of non-circular/non-spherical particles undergoing shear.     

Metal Fabrication by Additive Manufacturing Using Laser and Electron Beam Melting Technologies

Selective laser melting (SLM) and electron beam melting (EBM) are relatively new rapid, additive manufac- turing technologies which can allow for the fabrication of complex, multi-functional metal or alloy monoliths by CAD-directed, selective melting of precursor powder beds. By altering the beam parameters and scan strategies, new and unusual, even non-equilibrium microstructures can be produced; including controlled microstructural architectures which ideally extend the contemporary materials science and engineering paradigm relating structure-properties-processing-performance. In this study, comparative examples for SLM and EBM fabricated components from pre-alloyed, atomized precursor powders are presented. These include Cu, Ti–6Al–4V, alloy 625 (a Ni-base superalloy), a Co-base superalloy, and 17-4 PH stainless steel. These systems are characterized by optical metallography, scanning and transmission electron microscopy, and X-ray diffraction.     

The Influence of Morphology on Photo-catalytic Activity and Optical Properties of Nanocrystalline ZnO Powder

Nano-Micro Letters - ZnO nano-particles were synthesized via an ammonical ammonium carbonate solution by precipitation method in presence of some additives such as urea, oleic and stearic acid. The...     

The impact of a participatory ergonomics intervention: the value of involvement

This article presents the implementation of a participatory ergonomics (PE) approach in a multinational company in the northern side of Italy, aiming to improve ergonomics, well-being and production outcomes. The methodology used is based on the creation of a multi-disciplinary team to provide and discuss ergonomics’ solutions according to the physical problems of the workers involved and better manage the re-introduction of the workers in the line of production. The study consists of a longitudinal analysis before and after the plant redesign and the PE intervention. Some psychosocial variables as job satisfaction, perceived fatigue, perceived usefulness, repetitiveness, occupational safety and company attention to safety have been monitored to verify the impact of the PE intervention. The results show how the PE intervention positively influences the perception of workers regarding the level of fatigue and repetitiveness and increasing job satisfaction, usefulness and occupational safety with a positive impact on productivity.