Detection of protein A produced by Staphylococcus aureus with a fiber-optic-based biosensor

Staphylococcus aureus is a pathogen important in causing human infections and intoxication. A sensitive fiber-optic that produces evanescent waves was developed for the detection of protein A, a product secreted only by S. aureus. In the immunosensor, a 40-mV argon-ion laser that generated laser light at 488 nm was used together with plastic optical fiber and antibodies to protein A were physically adsorbed onto the fiber. The principle of the detection involved a sandwich immunoassay with fluorescein isothiocyanate conjugated with anti-(protein A) immunoglobulin G to produce signals of the antigen-antibody reaction. The detection limit was 1 ng of protein A per milliliter. The fiber-optic immunosensor could be used for rapid and specific detection of S. aureus in clinical specimens and foods.     

Hypoxia-ischemia induces a rapid elevation of ubiquitin conjugate levels and ubiquitin immunoreactivity in the immature rat brain

Postnatal rats at 7 and 21 days of age were subjected to unilateral hypoxia-ischemia (H/I) by right carotid artery ligation followed by 1.5 to 2 hours of hypoxia (8% oxygen). Brains were frozen at specific intervals of recovery from 0 to 24 hours. Western blots of samples of right and left forebrain were immunodeveloped with a monoclonal antibody specific for ubiquitin, RHUb1. An elevation of ubiquitin conjugate levels in the right compared with the left forebrain of 7-day-old animals was detectable immediately following H/I and increased by close to 60% of control level within 1 hour of recovery. The conjugate immunoreactivity remained at this level for 6 hours but had declined to control levels by 24 hours of recovery. No such increase was observed in response to hypoxia alone. Similar changes were observed in samples from the 21-day-old rat brain. However, the elevation of ubiquitin conjugate levels was of slower onset and persisted longer than observed for the 7-day-old animals. Immunocytochemical studies of brain fixed by immersion in formaldehyde/acetone/methanol showed that ubiquitin-like immunoreactivity was increased in the right, but not left, cerebral cortex and hippocampus of animals subjected to H/I. The data suggest that elevated ubiquitination may represent a neuroprotective response to H/I.     

Electrochemical oxidation of manganese(II) at a platinum electrode

Electrochemical oxidation of Mn²⁺ in sulphuric acid to form MnO₂ was studied using stationary and rotating platinum/platinum ring-disc electrodes. It appears that nucleation of MnO₂ is governed by an equilibrium involving a Mn(III) intermediate. Growth of MnO₂ involves the reduction of MnO₂ surfaces by Mn²⁺ ions in the solution to form MnOOH intermediates. The subsequent electrochemical oxidation of MnOOH releases a hydrogen ion and results in the formation of MnO₂. The rate constant of MnOOH oxidation to MnO₂ was estimated to be 40 s^–1. With a sufficient supply of Mn²⁺ ions, a layer of MnOOH is built up and the in-solid diffusion of hydrogen ions becomes the ratedetermining-step. With a low Mn²⁺ concentration, diffusion of Mn²⁺ ions from bulk electrolyte to the MnO₂/electrolyte interface is a factor controlling the growth of MnO₂. The activation energy and the pre-exponential term of the diffusion coefficient of Mn²⁺ in 0.5m sulphuric acid were determined to be 44.8 kJ mol^–1 and 100 cm² s^–1, respectively.     

Mesoporous silica with short-range MFI structure

A new type of mesoporous silica has been prepared which showed 780 m²/g of BET surface area and 0.6 ml/g of primary mesopores narrowly distributed around 4.2 nm. More importantly however, is that it showed short-range zeolite crystallinity as demonstrated by FTIR and XRD analysis, and hydrophobicity as demonstrated by water and n-hexane adsorption.

This material was synthesized via a dual-template, three-step hydrothermal–flocculation–steaming synthesis procedure developed by us recently. Briefly, MFI nanoprecursors (NPs) were first prepared by a low-temperature hydrothermal step using TPAOH as template for zeolite structure, and then flocculated using a surfactant that served as the template for the mesopores. The collected NPs are mesoporous silica exhibiting short-range MFI domains when directly calcined. However, the steaming step promoted the crystallization of the NPs and created uniform mesopores. It was found that almost every detail in these procedures affected the properties of the final product. The most important variables, however, were identified as the duration the flocculants were kept in contact with the liquid phase, and the humidity under which the steaming was conducted. By properly adjusting the procedures, the said mesoporous silica, as well as nanocrystals having high external surface area, could be produced at will.     

Formation and inhibition of free radicals in electrically stressed and aged insulating polymers

Previous work has shown that prebreakdown, electrical aging, and breakdown phenomena are directly associated with charge carriers injected from electrical contacts and their subsequent dissociative trapping and recombination. In addition, the energy released from each trapping or recombination event is dissipated in the breaking of the bonds of macromolecules, thus forming free radicals and new traps in the electrically stressed insulating polymers, as predicted by Kao's model. It is this gradual degradation process that leads to electrical aging and destructive breakdown. New experimental results are presented to confirm previous findings and a new approach to inhibit the degradation process by the incorporation of suitable dopants into the polymer. The concentration of free radicals in the polymer increases with an increasing electric field at a fixed stress time of 250 h and with increasing stress time at a fixed electric field of 833 kV cm^?1. The concentration of free radicals is directly related to the concentration of new traps created by stress. However, when suitable dopants are incorporated, the initiation voltage for the occurrence of electrical treeing and the breakdown strength are both increased. The dopants tend to create shallow traps and have little effect on the deep trap concentration. This implies that the dopants act as free‐radical scavengers that tend to satisfy the unpaired electrons of the broken bonds, which create new acceptor‐like electron traps and new shallow traps. By doing so, the shallow traps screen the deep traps, thereby reducing the energy released during trapping and recombination and the probability of breaking the macromolecular bonds and causing structural degradation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3416–3425, 2003     

Synergistic effects by compatibilization and annealing treatment of metallocene polyethylene/PLA blends

The properties of metallocene polyethylene (mPE)/polylactic acid (PLA) bio‐based blends containing an ethylene‐glycidyl methacrylate‐vinyl acetate (EGMA‐VA) compatibilizer, with or without the annealing effect of PLA were investigated. The results from SEM (Scanning electron microscope) morphology observation revealed that the dispersed PLA particles sizes within the mPE matrix tended to decrease with the added compatibilizer due to the enhanced interfacial interaction. DSC (Differential scanning calorimetry) and XRD (X‐ray diffractometer) results indicated that the addition of the compatibilizer completely hindered the cold crystallization and rearrangement crystallization of PLA, even though the additional annealing effect tended to increase the crystallization of PLA. Tensile test results showed the synergistic effects by compatibilization and annealing treatment improved the tensile strength and Young's modulus, up to 38 % and 62 % increase, respectively. With the incorporation of the compatibilizer, the viscosity increased and reached the highest level among all neat resins and blends, which was attributed to the enhanced interfacial interaction between mPE and PLA. Hopefully, the incorporated bio‐based PLA materials could be helpful in reducing the use of petroleum‐based materials and are beneficial to the environment in terms of the sustainable development concern. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2399–2409, 2013     

Optimization of Open-end Rotor Spinning Frame Parameter and Estimation of Relevant Quality Characteristics

The high-cleaning Lyocell fibers are used to spin the Ne 32 yarns for an open-end rotor spinning frame. The optimal processing parameters were obtained in demonstrating output speed, stretching roller speed, feed speed and rotor revolution. The quality characteristics, such as yarn count, strength, elongation and Um (%), are far beyond the rating standard of the combed yarn. No yarn breaking for continuous spinning during the experimental confirmation. The result presents lower yarn breaking rate and maintains stabilized output status of spinning conditions. The back propagation neural network was employed for learning, forecast and verification of the processing parameters.     

Low-surface-free-energy polybenzoxazine/polyacrylonitrile fibers for biononfouling membrane

We blended poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PBA) into polyacrylonitrile (PAN) to generate low-surface-free-energy fibers without fluorine and silicon elements for electrospinning. Liquid-state BA at room temperature can be solidified in electrospinning process using PAN as a medium through their miscible behavior. Results indicate that the mixing below 50 wt% BA into PAN matrix for electrospinning has no significant dropping beads, indicated a miscible PAN/BA system. Above 70 wt% BA in PAN solution could not be solidified completely after electrospinning, revealed apparent beaded fibers. The PAN/PBA blend fibers, obtained after curing at 300 °C, generated a superhydrophobicity because of the low-surface-free-energy PBA. In addition, laser scanning confocal microscope (LSCM) measurements were included to determine the relative amount of antibody that adsorbed to these PAN/PBA fibers to examine the biofouling-resistant property. The results showed an obviously decreased protein adsorption with increasing PBA fraction. The correlations between PAN and PBA would provide insight into the designing and developing of low-surface-free-energy fibers without fluorine and silicon elements to improve biofouling-resistant property.     

A Century of Production and Application of Light

THE conquest of dark by means of artificial illumination is considered one of the all-time greatest achievements of mankind. Nothing much can be accomplished in a dark environment. Over one hundred years ago, illuminating gas, carbon arcs, candles, kerosene, and other types of oil lamps were the most widely used artificial light in the world. In 1879, Edison invented the first practical electric lamp. This incandescent lamp marked the beginning of the electrical lighting industry.