Hot-nanoparticle-mediated fusion of selected cells

Complete fusion of two selected cells allows for the creation of novel hybrid cells with inherited genetic properties from both original cells.Alternatively,via fusion of a selected cell with a selected vesicle,chemicals or genes can be directly delivered into the cell of interest,to control cellular reactions or gene expression.Here,we demonstrate how to perform an optically controlled fusion of two selected cells or of one cell and one vesicle.Fusion is mediated by laser irradiating plasmonic gold nanoparticles optically trapped between two cells (or a vesicle and a cell) of interest.This hot-particle-mediated fusion causes total mixing of the two cytoplasms and the two cell membranes resulting in formation of a new hybrid cell with an intact cell membrane and enzymatic activity following fusion.Similarly,fusion between a vesicle and a cell results in delivery of the vesicle cargo to the cytoplasm,and after fusion,the cell shows signs of viability.The method is an implementation of targeted drug delivery at the single-cell level and has a great potential for cellular control and design.     

Expanding the optical trapping range of gold nanoparticles

We demonstrate stable three-dimensional (3D) single-beam optical trapping of gold nanoparticles with diameters between 18 and 254 nm. Three-dimensional power spectral analysis reveals that, for nanoparticles with diameters less than 100 nm, the trap stiffness is proportional to the volume of the particle. For larger particles, the trap stiffness still increases with size, however, less steeply. Finally, we provide numbers for the largest forces exertable on gold nanoparticles.     

Quantitative optical trapping of single gold nanorods

We report a quantitative analysis of the forces acting on optically trapped single gold nanorods. Individual nanorods with diameters between 8 and 44 nm and aspect ratios between 1.7 and 5.6 were stably trapped in three dimensions using a laser wavelength exceeding their plasmon resonance wavelengths. The interaction between the electromagnetic field of an optical trap and a single gold nanorod correlated with particle polarizability, which is a function of both particle volume and aspect ratio.     

Enzymatic biodiesel production: Technical and economical considerations

It is well documented in the literature that enzymatic processing of oils and fats for biodiesel is technically feasible. However, with very few exceptions, enzyme technology is not currently used in commercial‐scale biodiesel production. This is mainly due to non‐optimized process design and a lack of available cost‐effective enzymes. The technology to re‐use enzymes has typically proven insufficient for the processes to be competitive. However, literature data documenting the productivity of enzymatic biodiesel together with the development of new immobilization technology indicates that enzyme catalysts can become cost effective compared to chemical processing. This work reviews the enzymatic processing of oils and fats into biodiesel with focus on process design and economy.     

USE OF FLOW CYTOMETRY FOR RAPID ESTIMATION OF INTRACELLULAR EVENTS IN BREWING YEASTS

A flow cytometric method based on staining with fluorescein diacetate (FDA) for rapid measurement of the fluorescence intensity (FI) of individual brewing yeast cells is reported. Distinct changes in the FI of yeast populations during the course of both laboratory scale and brewery fermentations were observed. The changes followed a characteristic pattern defined as the FI-profile. The FI-profile was related to the rate of attenuation as well as changes in yeast glycogen and ergosterol contents. The results obtained suggest that flow cytometry can be applied for estimation of intracellular events in brewing yeasts and prediction of their performance.     

MMPI-2 random responding indices: Validation using a self-report methodology.

Investigated the validity of F, back F, and variable response inconsistency indices of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) for detection of self-reported partially random responding in several samples, including college students, community volunteers, and job applicants. Substantial numbers of Ss admitted to providing some random responses, with 29–60% of the various samples acknowledging an average of 12–38 random responses in their MMPI-2 answers. For all groups, with the expected exception of job applicants, the appropriate MMPI-2 validity indices were reliably and positively correlated with self-estimates of random responses. Available data suggested that random responding occurred most commonly toward the end of the test, although significant numbers indicated that they had scattered their random responses throughout the test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reduced combustion efficiency of chlorinated compounds,resulting in higher yields of carbon monoxide

A series of experiments involving the combustion of inherently fire-retarded compounds has been performed using the DIN 53 436 furnace. Six chlorinated compounds comprising four pesticides, an organic solvent, and polyvinyl chloride (PVC) have been investigated with the focus on the combustion efficiency expressed as the CO₂/CO ratio in the fire effluent. It was found that increased chloride content in a compound resulted in decreased CO₂/CO ratio. The correlation was found to be $ \sqrt {{\rm CO}_{\rm 2} /{\rm CO}} = 0.61 \times ({\rm Cl/C)}^{- {\rm 1}} + 0.13 $. The results indicate higher concentrations of CO in the fire effluent from chlorinated compounds than from wood. Together with a release of HCI this could result in an increased toxic potency. The overall toxic hazard may or may not be increased, since (inherently) fire-retarded materials tend to have an improved fire performance.     

Crystallization of ZBLAN Glass

The glass transition, onset crystallization, solidus, and liquidus temperatures of a ZBLAN glass have been measured by differential thermal analysis in a sealed Pt ampoule. The onset crystallization was observed at 335°C for a powdered glass, while for a monolithic glass, prepared by in situ quenching in the Pt capsule, the onset crystallization was observed at 395°C, 135°C higher than T _g. Surface-induced heterogeneous nucleation is therefore proposed to be important for the crystallization of ZBLAN glasses. The solidus temperature was observed at 452°C, about 10°C lower than reported for the subsystem ZrF₄–BaF₂–NaF.     

Subcritical drying of silica gels

Silica aerogel is a sol-gel prepared material characterized by high porosity and large inner surface area. Aerogels can be prepared with a high transparency and low thermal conductivity, giving a material excellent for application as transparent thermal insulator. The traditional route to prepare silica aerogels is by formation of an alcogel by hydrolysis and condensation of silicon alkoxides followed by supercritical drying in an autoclave at high pressure (–100 atm). Unfortunately, this process is expensive and might be dangerous, so drying methods have been developed that operate under ambient conditions. In previous work, we have shown that gels can be strengthened and stiffened by providing new monomers to the alcogel giving xerogels with similar properties as aerogels by drying at ambient pressure (porosity up to 90%). This method of obtaining ambient pressure dried aerogels will be described and special emphasis will be given on the effect of the initial gel structure on the preparation of the xerogels.