Development of an amperometric l-lactate biosensor based on l-lactate oxidase immobilized through silica sol–gel film on multi-walled carbon nanotubes/platinum nanoparticle modified glassy carbon electrode

Platinum nanoparticles (Ptnano) were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical l-lactate biosensor. The composite film of MWCNTs and Ptnano was dispersed on the surface of the glassy carbon electrode (GCE). l-lactate oxidase (LOD) was immobilized on MWCNTs/Ptnano/GCE surface by adsorption. The resulting LOD/MWCNTs/Ptnano electrode was covered by a thin layer of sol–gel to avoid the loss of LOD in determination and to improve the anti-interferent ability. Moreover, the sol–gel microenviroment contributes to both intensified stability and permselectivity. The cyclic voltammetry results indicated that MWCNTs/Ptnano catalyst displayed a higher performance than MWCNTs. Under the optimized conditions of applied potential 0.5 V, pH 6.4, room temperature, the proposed biosensor showed a large determination range (0.2–2.0 mM), a short response time (within 5 s), a high sensitivity (6.36 μA mM^{− 1}) and good stability (90% remains after 4 weeks). The fabricated biosensor had practically good selectivity against interferences. The results for whole blood samples measured by the present biosensor showed a good agreement with those measured by spectrophotometric method.     

Sugar response of boronic acid-substituted azobenzene dye-modified polymer

We synthesized a boronic acid-appended azobenzene dye (BA) and attached it to poly(ethyleneimine) (polyBA) for studying its sugar response. The addition of d-glucose induced a significant change in the UV–visible absorption spectra of the polyBA solution. The binding constants for d-glucose (K_glu) and d-fructose (K_fru) were calculated to be 54 M^? 1 and 110 M^? 1, respectively. The selectivity for d-glucose was higher in polyBA as compared with that of monomeric BA (K_glu = 1.2 M^? 1, K_fru = 17 M^? 1). We also fabricated multilayered films composed of polyBA and polyanions {poly(vinyl sulfate) (PVS), carboxymethylcellulose (CMC)} using a layer-by-layer deposition technique. In (PVS/polyBA)₁₀ films, the affinity for d-glucose was relatively low (K_glu = 1.7 M^? 1, K_fru = 28 M^? 1). In contrast, (CMC/polyBA)₅ films showed a high affinity for d-glucose (K_glu = 18 M^? 1, K_fru = 42 M^? 1). The loosely packed structure of the (CMC/polyBA)₅ film and the suitable chemical structures of CMC probably led to a high affinity for d-glucose.     

Antisense knockdown of spinal-mGluR1 reduces the sustained phase of formalin-induced nociceptive responses

To examine the role of mGluR1 (a subunit of the group I metabotropic glutamate receptor) in the nociceptive responses of rats following a subcutaneous injection of formalin into the plantar surface of the hind paw, we delivered antisense oligonucleotides (ODNs) against mGluR1 into the rat lumbar spinal cord (L3-L5) intrathecally using an HVJ-liposome-mediated gene transfer method. Rats treated with a single injection of mGluR1 antisense ODNs into the intrathecal space of the lumbar spinal cord showed a marked reduction of the early-sustained phase of formalin-induced nociceptive responses, but not of their acute phase. The reduction of nociceptive behavioral responses became apparent at day 2 after the antisense treatment and lasted for 2 days. This corresponded to a long-lasting down-regulation (46%) of mGluR1 expression in the lumbar cord. This down-regulated mGluR1 was observed at day 2 and persisted until day 4 after the intrathecal infusion of mGluR1 antisense ODN. In contrast, rats treated with mGluR1 sense or mismatch ODNs showed none of these changes. These results suggest that mGluR1 may play a crucial role in the sustained nociception of formalin-induced behavioral responses.     

Recurrent annular erythema in juvenile chronic myelogenous leukaemia

Juvenile chronic myelogenous leukaemia (JCML) is a rare haematological malignancy of myelomonocytic lineage that affects patients less than 4 years of age and is known as an entity different from adult-type chronic myelogenous leukaemia. In JCML, skin manifestations are relatively common but most of them have been reported as a non-specific eruption, which histologically may show changes resembling neurofibromatosis or xanthogranuloma. We present a 2-year-old boy with JCML who developed a recurrent annular erythema in which leukaemic infiltrates were confirmed histologically, even though his bone marrow examination suggested that be remained in haematological remission.     

Evaluation of hydrogen-assisted cracking behavior of low-alloy steel in the range 95 °C to 350 °C

In this report, hydrogen-assisted cracking (HAC) behavior of low-alloy steel was evaluated using a constant elongation rate tensile test, and the temperature and crack tip strain rate effects were observed. It was found that temperature dependence of the threshold condition (C _σm ^c ) of HAC above about 100 °C followed the relation C _σm ^c = Kexp(−41,300/Rr) whereK is a constant andT is absolute temperature. The relationship between HAC growth rate and crack tip strain rate was established as almost linear, irrespective of temperature and hydrogen concentration at the crack tip. Hydrogen heat release tests were also performed. From these tests, formation and growth of microcracks which are trap sites of hydrogen were thought to be the mechanism of HAC in the steel. From this mechanism, HAC behavior of the low-alloy steel could be qualitatively explained.     

Developing a Lisp‐based preprocessor for TEX documents

TEX allows users to define a macro that abstracts a sequence of typesetting commands. However, defining macros is not easy for most users, because the mechanism of macro expansion in TEX is complicated. As a remedy for this situation, a new system that enables users to define macros for TEX documents as Lisp programs has been developed. The system acts as a preprocessor for TEX; given a document that contains Lisp programs as S‐expressions, the system expands each S‐expression on the basis of Lisp's evaluation rules, thus generating an ordinary TEX document. The system is very flexible and easy‐to‐use, thanks to the underlying language's general‐purpose data structure, i.e. the S‐expression, applicative order evaluation, and rich set of predefined functions. This paper also demonstrates that the proposed system is really effective for practical use by giving some concrete examples of Lisp macros, some of which are difficult to define in terms of TEX commands. The system is currently implemented on the Emacs Lisp, and a user‐friendly environment is thus available in the Emacs text editor. Copyright © 2002 John Wiley & Sons, Ltd.     

Upper Critical Field of Organic Superconductor κ-(ET)2Cu(NCS)2 Determined by Specific Heat Measurements

Both specific heat and resistance measurements of organic superconductor -(ET)₂Cu(NCS)₂ under magnetic field were performed. Upper critical fields, obtained from the specific heat data, are significantly less than those from the magnetoresistance measurements. At temperatures below 2 K and magnetic fields below 1 T, we observed additional power dissipation due to the field sweep. This effect may be attributed to the existence of irreversibility line.     

Use of polymeric indicator for electrochemical DNA sensors: poly(4-vinylpyridine) derivative bearing [Os(5,6-dimethyl-1,10-phenanthroline)2Cl]2+

A poly(4-vinylpyridine) (PVP) derivative bearing redox-active osmium complexes, PVP-[Os(5,6-dmphen)(2)Cl](2+) (5,6-dmphen = 5,6-dimethyl-1,10-phenanthroline), was employed as a hybridization indicator for electrochemical DNA sensors. PVP-[Os(5,6-dmphen)(2)Cl](2+) exhibited approximately 1000 times higher sensitivity than the corresponding monomeric analogue, [Os(5,6-dmphen)(3)](2+), in DNA determination due to polymeric effects. The detection limit of the present sensor was approximately 0.5 amol. Another merit of the polymeric indicator is that the redox potential was found to be +360 mV (vs Ag/AgCl), which is significantly lower than that reported for the monomeric analogue (+672 mV). The polymeric indicator was applicable to the discrimination of single- and double-base-mismatched DNAs from fully matched target DNA. The polymeric indicator can be removed from the electrode surface by rinsing the electrode in a high-temperature buffer for 6 min, and thus, the polymeric indicator-based DNA sensor can be used repeatedly.     

Reaction field analysis of a non-thermal plasma flowing in a rectangular reactor

Chemical reactive fields of non-thermal plasma flowing were clarified by using both experimental and numerical methods in the present study. The plasma was generated by using needle-plate electrodes with applied voltage of 12 kV and a square wave of 20 Hz. The operating gas was air injected at a rate of 1-10 Sl/min through a rectangular reactor with a 3×7 mm cross section. Distributions of gas velocity, gas temperature and NO concentration were clarified by experimental and numerical methods. The NO concentration was strongly influenced by the gas flow rate, because the N concentration was rapidly decreased in the case of small gas flow rate.