Lowering ambient or core body temperature elevates striatal MPP+ levels and enhances toxicity to dopamine neurons in MPTP-treated mice

The neuroprotective effects of lowering body temperature have been well documented in various models of neuronal injury. The present study investigated the effects a lower ambient or core body temperature would have on damage to striatal dopamine (DA) neurons produced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Mice received systemic MPTP treatment at two different temperatures, 4 degrees C and 22 degrees C. MPTP-treated mice maintained at 4 degrees C demonstrated (1) a greater hypothermic response, (2) a significant reduction in striatal DA content and tyrosine hydroxylase (TH) activity, and (3) significantly greater striatal 1-methyl-4-phenylpyridinium (MPP+) levels, as compared to mice dosed with MPTP at room temperature. Parallel studies with methamphetamine (METH) were conducted since temperature appears to play a pivotal role in the mediation of damage to DA neurons by this CNS stimulant in rodents. As previously reported, METH-induced hyperthermia and the subsequent loss of striatal DA content were attenuated in animals dosed at 4 degrees C. We also evaluated the effects a hypothermic state induced by pharmacological agents would have on striatal neurochemistry and MPP+ levels following MPTP treatment. Concurrent administration of MK-801 or 8-OHDPAT increased the striatal MPP+ levels following MPTP treatment. However, only 8-OHDPAT potentiated the MPTP-induced decrements of striatal DA content and TH activity; MK-801 did not affect MPTP decreases in these striatal markers of dopaminergic damage. Altogether, these findings indicate that temperature has a profound effect on striatal MPP+ levels and MPTP-induced damage to DA neurons in mice.     

Selection of weight quantisation accuracy for radial basis function neural network using stochastic sensitivity measure

Minimising the number of bits per connection weight in hardware realisation of a radial basis function neural network (RBFNN) will result in high-speed and low-cost implementation, with possible increase in output error. A weight quantisation accuracy selection method is proposed, to find an appropriate number of bits for a given stochastic sensitivity measure, which quantifies the relationship between the variance of the output error and first- and second-order statistics of input, weight and their perturbations.     

Repeated subacute ozone exposure of inbred mice: airway inflammation and ventilation

The present study was designed to assess the effects of repeated subacute ozone (O3) exposure on pulmonary inflammation and ventilation in two inbred strains of mice differentially susceptible to a single O3 exposure. Susceptible C57BL/6J (B6) and resistant C3H/HeJ (C3) mice were exposed to 0.3 ppm O3 for 48 and 72 h and, after 14 days recovery, both strains were reexposed. Airway inflammation and lung injury were assessed by counting inflammatory cells and measuring total protein content and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage (BAL) returns. Minute ventilation [VE, the product of breathing frequency (f), and tidal volume (VT)] was measured prior to and immediately following each exposure. After the initial exposure, B6 mice developed greater O3-induced increases in total protein, inflammatory cell influx, and LDH activity compared to C3 mice. In normal air, VE was also significantly elevated in B6, but not C3, mice after O3. The hypercapnic f of B6 and hypercapnic VT of C3 mice were significantly altered after O3 exposure. Reexposure to O3 caused a smaller increase in the numbers of macrophages, lymphocytes, epithelial cells, and BAL protein in both strains, and no changes in LDH activity. However, the number of polymorphonuclear leukocytes significantly increased in B6 and C3 mice as compared to the initial O3 exposure. In both strains, the ventilatory responses to normal air or hypercapnia were largely reproducible after O3 reexposure. Results indicated that differential susceptibility to O3-induced inflammation was maintained in B6 and C3 mice with O3 reexposure although the magnitude of the difference was reduced. Results also suggest that the ventilatory responses to O3 in B6 and C3 mice were reproducible with reexposure, and that airway inflammation and ventilation were not codependent.     

Quantitative imaging of gene expression in individual bacterial cells by chemiluminescence

Recent gene expression studies at the single bacterial cell level have primarily used green fluorescent protein (GFP) as the reporter. However, fluorescence monitoring has intrinsic limitations, such as GFP maturation time, high background, and photobleaching. To overcome those problems, we introduce the alternative approach of chemiluminescence (CL) detection with firefly luciferase as the probe. Firefly luciferase is roughly 100 times more efficient and is faster in generating CL than bacterial luciferase but requires the introduction of luciferin, a species that is not native to bacteria. The difficulty of luciferin diffusion into the cells was solved by making use of cell membrane leakage during bacteria dehydration. In this scheme, the overall sensitivity of the system approaches the single protein molecule level. Quantitative studies of gene expression in BL21 and XLU102 bacteria can thus be performed.     

Crystallization and melting behavior of the crystalline soft segment in a shape‐memory polyurethane ionomer

To illustrate the crystallization properties of soft segments in shape‐memory polyurethane (SMPU) ionomers, a series of SMPU ionomers with various ionic group contents and two kinds of counterions were synthesized with a prepolymerization method. An isothermal crystallization kinetic method was used to analyze the effects of ionic groups within the hard segments on the crystallization of the soft segments in a heating and cooling routine similar to that in a shape‐memory function. The more ionic groups there were within the hard segments, the lower the crystallization rate was of the soft segments. The crystallization mechanism of the SMPU ionomers was quite close to that of a control sample on the basis of similar Avrami exponents; the counterion category also had some influence on the crystallization rate. Meanwhile, the melting behavior after isothermal crystallization reflected the fact that the thermal history of the hard segments had a huge effect on the crystallization mechanism of the soft segments. Especially for the SMPU ionomer quenched from 240°C, the crystallization time dependence of the secondary crystallization was rather significant, but for the SMPU ionomer quenched from 70°C, the primary crystallization of the poly(?‐caprolactone) soft segment was predominant. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

New plasma surface-treated memory alloys: Towards a new generation of “smart” orthopaedic materials

This paper describes the corrosion resistance, surface mechanical properties, cyto-compatibility, and in-vivo performance of plasma-treated and untreated NiTi samples. Nickel–titanium discs containing 50.8% Ni were treated by nitrogen and carbon plasma immersion ion implantation (PIII). After nitrogen plasma treatment, a layer of stable titanium nitride is formed on the NiTi surface. Titanium carbide is also found at the surface after carbon plasma implantation. Compared to the untreated samples, the corrosion resistances of the plasma PIII samples are better by a factor of five and the surface hardness and elastic modulus are better by a factor of two. The concentration of Ni leached into the simulated body fluids from the untreated samples is 30 ppm, whereas that from the plasma-treated PIII are undetectable. Although there is no significant difference in the ability of cells to grow on either surface, bone formation is found to be better on the nitrogen and carbon PIII sample surfaces at post-operation 2 weeks. All these improvements can be attributed to the formation of titanium nitride and titanium carbide on the surface.     

Surface structure and biomedical properties of chemically polished and electropolished NiTi shape memory alloys

The surface structure and biomedical properties of NiTi shape memory alloy (SMA) samples after undergoing electropolishing and chemical polishing are determined and compared employing scanning electron microscopy, X-ray photoelectron spectroscopy, inductively-coupled plasma mass spectrometry, hemolysis analysis, blood platelet adhesion test, and MTT test. The results indicate that after chemical polishing, there is still a high Ni concentration on the surface of the NiTi SMA. On the other hand, electropolishing can form a thin surface titanium oxide film (about 10 nm thickness) with depleted Ni. In addition to the TiO₂ phase, some titanium suboxides (TiO and Ti₂O₃) are found in the surface film. Compared to chemical polishing, electropolishing can more effectively mitigate out-diffusion of Ni ions and the wettability, blood compatibility, and thromboresistance are also better. However, no difference on the cytocompatibility can be observed from samples that have been chemically polished or electropolished.     

Non-destructive Evaluation of Adhesive Bonding Using Reflective Fringe Pattern Technique

Adhesive bonding is an important fabrication technique for traditional and modern engineering materials in most industrial applications. Compared to the traditional joining methods (such as mechanical fastening or welding), adhesive bonding is rather simple, low cost and time-saving. The performance of the adhesive bonded assemblies strongly depends upon both the material and adhesive properties, and also the bond quality. An excessive gap between the joined elements could result in local stress concentration, and consequently reduce the bond strength. This paper suggests a full-field and optical technique, Reflective Fringe Pattern (RFP) technique, for evaluating adhesive bonding. RFP is based on reflecting the fringe pattern from a specularly reflective surface. In the measurement, two sets of the reflected fringe patterns (i.e. one before and the other after deformation) are recorded to produce the corresponding fringe phase distributions. The difference of these phase distributions depicts the surface deformation. As an adhesive disbond affects the surface deformation, the presence of adhesive disbond can be located by identifying the flaw-induced deformation anomalies in the phase-change distribution map. The potential of using RFP for inspecting adhesive bonding is demonstrated and compared with the conventional non-destructive testing technique—thermography.     

Sustainability issues in the industrial heritage adaptive reuse: rethinking culture-led urban regeneration through Chinese case studies

Targeted at the fragility of culture-led regeneration as a result of market frustrations and policy instability, the paper proposes a sustainable perspective to re-examine the prospects of culture-led urban regeneration projects at the local level through the taxonomy of three signatures—The Beijing 798 Art Zone, The Shanghai M50 and The Guangzhou Xinyi International Club are chosen as different, yet representative cases of industrial heritage transformed creative clusters. By comparing the development trajectories and statuses of these pioneer culture-led regeneration projects, the paper reveals the mechanism and confirms the model of practice for the reincarnation of industrial heritage by creative clusters in the local context of the cities. Ultimately, the analysis of this model indicates that the reuse of industrial heritage is an effective approach in response to the cultural demands of the post-industrial era; however, it brings forth the inevitable challenges beyond economic dimension, from a sustainability perspective. The analysis further identifies those underlying reasons of unsustainability and provides recommendations in order to explore the full potential of the “cultural value” of urban regeneration.