Sonographic probing of laser filaments in air

The acoustic wave emitted from the plasma channel associated with a filament induced by a femtosecond laser pulse in air was detected with a microphone. This sonographic detection provides a new method to determine the length and the spatial profile of the free-electron density of a filament. The acoustic wave is emitted owing to the expansion of the gas in the filament, which is heated through collisions with high-energy photoelectrons generated by multiphoton ionization. Compared with other methods, the acoustic detection is simpler, more sensitive, and with higher spatial resolution, making it suitable for field measurements over kilometer-range distances or laboratory-scale studies on the fine structure of a filament.     

A comparative study of antitumour and toxicologic properties of related polyanions

Poly(maleic anhydride) (PMA) homopolymer, DIVEMA copolymer (PCP) and poly(acrylic acid—maleic anhydride) (PAAMA) copolymer were synthesised and separated into discrete molecular weight (MW) fractions. These fractions were tested for antitumour (Lewis lung carcinoma LLC), anti-Friend leukemia (FLV), immunoadjuvant activity, phagocytic activity, sensitization to bacterial lipopolysaccharide (LPS) and inhibition of microsomal mixed functional oxidase enzymes (MMFO). Molecular weight preparations of the three polymers, 10 000 and above, possess pronounced activity against LLC (increased life-span > 35%), FLV (ED₅₀ between 1.6–4.0 mg/kg) and enhanced B lymphocyte activity as measured by increased number of hemolytic plaque forming cells. Molecular weight preparations below 1000 were devoid of these activities. PCP was the most potent inhibitor of MMFO as measured by prolongation of hexabarbital sleeping times. All polymers induced a sensitization to LPS. PCP was the most potent sensitizer followed by PAAMA and PMA. PCP at MW 30 000 and above markedly suppressed phagocytosis as measured by the vascular clearance rate of colloid carbon in mice while MW preparations <5000 >2000 stimulated phagocytosis. PMA inhibited phagocytosis to a much lesser degree than PCP. In contrast to PCP, PMA did not stimulate phagocytosis until 7 days after drug administration. Peritoneal exudate cells (PEC) and serum from PCP and PMA-treated mice conferred complete protection against FLV but not LLC in recipient mice. Supernatants from the PEC also transferred protection but not to the same degree as whole cells. These studies begin to delineate the structures and polymer size which possess therapeutic and toxicologic potential.     

Gene expression in peripheral arterial chemoreceptors

The peripheral arterial chemoreceptors of the carotid body participate in the ventilatory responses to hypoxia and hypercapnia, the arousal responses to asphyxial apnea, and the acclimatization to high altitude. In response to an excitatory stimuli, glomus cells in the carotid body depolarize, their intracellular calcium levels rise, and neurotransmitters are released from them. Neurotransmitters then bind to autoreceptors on glomus cells and postsynaptic receptors on chemoafferents of the carotid sinus nerve. Binding to inhibitory or excitatory receptors on chemoafferents control the electrical activity of the carotid sinus nerve, which provides the input to respiratory-related brainstem nuclei. We and others have used gene expression in the carotid body as a tool to determine what neurotransmitters mediate the response of peripheral arterial chemoreceptors to excitatory stimuli, specifically hypoxia. Data from physiological studies support the involvement of numerous putative neurotransmitters in hypoxic chemosensitivity. This article reviews how in situ hybridization histochemistry and other cellular localization techniques confirm, refute, or expand what is known about the role of dopamine, norepinephrine, substance P, acetylcholine, adenosine, and ATP in chemotransmission. In spite of some species differences, review of the available data support that 1). dopamine and norepinephrine are synthesized and released from glomus cells in all species and play an inhibitory role in hypoxic chemosensitivity; 2). substance P and acetylcholine are not synthesized in glomus cells of most species but may be made and released from nerve fibers innervating the carotid body in essentially all species; 3). adenosine and ATP are ubiquitous molecules that most likely play an excitatory role in hypoxic chemosensitivity.     

Co-application of hydroxyalkyl dyes and polyphosphonic acids to cotton to achieve dye—fibre covalent bonding

The dyeing of cotton to a high standard of wet-fastness with hydroxyalkyl dyes and a polyphosphonatecrosslinker system has been investigated. Dyes containing hydroxyalkyl groups were prepared, by the reaction of commercial reactive dyes with ethanolamine, and applied to cotton fabric in the presence of polyphosphonic acid crosslinking agents using cyanamide as a catalyst. The application was carried out using a pad-thermosol method. The effects of cyanamide concentration, the nature of the crosslinker and the type of hydroxyalkyl dye were studied in detail. It was concluded that multifunctional polyphosphonates are capable of producing dyeings on cellulosic fibres exhibiting a high degree of covalent bonding (fixation). The efficiency of dye fixation at ca. 2% pure dye (owf), obtained from this method, was greater than 90%.     

Gap instability of laminar flows in eccentric annular channels

Flow visualization has demonstrated that the critical Reynolds number for flow instability in the narrow gap of an annular channel with a diameter ratio of about 0.28 increases with increasing eccentricity e in the range 0.5 < e < 0.8. The critical Reynolds numbers in the wide gap at all eccentricities and in the narrow gap for 0 < e < 0.5 seem to be insensitive to eccentricity. These observations and comparison of the frequencies of transverse flow oscillations at different Reynolds numbers and different eccentricities demonstrate that at least two distinct instability mechanisms are present in annular flows. The one of particular interest in this work arises in narrow gaps and is attributed to the instability of the two shear layers forming on either side of the gap. Linear stability analysis demonstrated that the basic flow in concentric annuli is stable for the considered diameter ratio and range of Reynolds numbers. In contrast, the basic flow in eccentric annuli has an azimuthal variation that contains two inflection points, thus being potentially linearly unstable.     

Functionalization of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) films via surface‐initiated atom transfer radical polymerization: Comparison with the conventional free‐radical grafting procedure

We modified hydrophobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV) films with hydrophilic chains to control their surface properties. We designed and investigated surface‐initiated atom transfer radical polymerization (SI‐ATRP) to modify the PHBHV films by grafting poly(2‐hydroxyethyl methacrylate) (PHEMA) from the surface. This method consisted of two steps. In the first step, amino functions were formed on the surface by aminolysis; this was followed by the immobilization of an atom transfer radical polymerization initiator, 2‐bromoisobutyryl bromide. In the second step, the PHEMA chains were grafted to the substrate by a polymerization process initiated by the surface‐bound initiator. The SI‐ATRP technique was expected to favor a polymerization process with a controlled manner. The experimental results demonstrate that the grafting density was controlled by the reaction conditions in the first step. The grafted films were analyzed by Fourier transform infrared spectroscopy, contact angle testing, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The results show that grafted chains under the SI‐ATRP method were preferentially located on the surface for surface grafting and in the bulk for conventional free‐radical polymerization initiated by benzoyl peroxide. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Semi-automated sample preparation for plasma proteomics

The discovery of new biomarkers will be an essential step to enhance our ability to better diagnose and treat human disease. The proteomics research community has recently increased its use of human blood (plasma/serum) as a sample source for these discoveries. However, while blood is fairly non-invasive and readily available as a specimen, it is not easily analyzed by liquid chromatography (LC)/mass spectrometry (MS), because of its complexity. Therefore, sample preparation is a crucial step prior to the analysis of blood. This sample preparation must also be standardized in order to gain the most information from these valuable samples and to ensure reproducibility. We have designed a semi-automated and highly parallel procedure for the preparation of human plasma samples. Our process takes the samples through eight successive steps before analysis by LC/MS: (1) receipt, (2) reformatting, (3) filtration, (4) depletion, (5) concentration determination and normalization, (6) digestion, (7) extraction, and (8) randomization, triplication, and lyophilization. These steps utilize a number of different liquid handlers and liquid chromatography (LC) systems. This process enhances our ability to discover new biomarkers from human plasma.     

Effectiveness of Portable Indoor Air Cleaners: Sensory Testing Results

The objective of this study was to test the effectiveness of individual commercially available portable indoor air cleaning units in removing dust particulates, tobacco smoke particulate and vapor phase constituents (nicotine and vinyl pyridine), viable and total fungal spores, pollen, and gaseous contaminants (carbon monoxide[CO], nitrogen dioxide[NO²], and formaldehyde[HCHO]), in a clean air test chamber. The air cleaner chamber results presented here represent initial-use results. In general, High Efficiency Particulate Air (HEPA) and electrostatic precipitator systems demonstrated the highest efficiencies with respect to particulate, contaminants, followed closely by electret filter systems. Ionizers and ozone generators were least effective in particulate removal. Systems which included sufficient sorbent material (i.e. activated carbon or potassium permanganate) were marginally effective at gaseous contaminant removal. None of the systems tested were effective at carbon monoxide removal. Sensory testing was conducted to discern potential correlation between human perceptive response and measured air cleaner performance (with respect to tobacco smoke removal). An electret filter (EF) loaded with carbon sorbent received the best ratings with respect to odor strength, nasal irritation, eye irritation, and overall air acceptability.     

Amperometric ATP microbiosensors for the analysis of chemosensitivity at rat carotid bodies

The physiological application of amperometric adenosine triphosphate (ATP) microbiosensors for characterizing the stimulus-response at rat carotid bodies superfused with high potassium concentrations, during normoxic hypercapnia, and during hypoxia is demonstrated using the peripheral arterial chemoreceptors in the carotid body of rats as a model system. Amperometric microbiosensors based on glucose oxidase (GOD) and hexokinase (HEX) immobilized within a polymer matrix at the surface of Pt disk microelectrodes (diameter: 25 microm) are positioned at a distance of approximately 100 microm above the carotid body surface for detecting extracellular ATP. A linear calibration function of ATP microbiosensors in the physiologically relevant concentration range of 0-40 microM ATP enables quantitative detection of ATP released at the carotid body surface in response to physiological stimuli. It is shown that these stimuli induce extracellular ATP release from the carotid body at levels of 4-10 microM. Other electroactive neurotransmitters such as, e.g., catecholamines are coreleased by the carotid body at hypercapnic, hypoxic and high-potassium stimulus, are simultaneously detected utilizing a dual-electrode assembly with an ATP microbiosensor and a second bare channel providing a colocalized reference measurement for ATP quantification.     

High glass transition temperature bio-based copolyesters from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and isosorbide

New renewable copolymers were prepared from reactive bis-hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) oligomers (PHBHV-diol), isosorbide and 1,4-phenylene diisocyanate. First, microwave (MW)-assisted alcoholysis in the presence of ethylene glycol provides a rapid and straightforward method for engineering PHBHV-diol, with molar masses ranging from 700 to 4100 g mol^?1. These well-defined oligoesters were further used for the preparation of random copolymers of PHBHV-diol and isosorbide bridged with 1,4-phenylene diisocyanate via urethanization. The molar masses (M_n) of most copolyesters are about 10,000 g mol^?1 with polydispersities (DPI) in the range of 1.2–1.9. The dependence of the solid-state structures on the length of PHBHV block was carefully investigated. The incorporation of isosorbide units into the PHBHV backbone increased the glass-transition temperatures from +5 °C up to +34 °C.