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51.
Researchers carrying out non-therapeutic research that involves the administration of drugs of abuse to human volunteers can be faced with many ethical and practical questions. The history of this type of research is relatively brief, with little in the way of published information relevant to carrying out behavioral pharmacological research with human participants. The aim of this article is to raise issues that occur in most studies of this type and to provide solutions that we have found acceptable and which have been approved by a variety of institutions and regulatory agencies. Clearly, there are other approaches that would work equally as well, and we are not attempting to provide 'the' answer to many of the issues raised. We believe that raising these issues and providing our perspectives is important for stimulating others to discuss them and for all of us to strive, where possible, to reach a consensus concerning ethical practices and to become aware of gaps and pitfalls. The topics discussed range from the nuts and bolts of acquiring and keeping track of drugs, to selecting research participants and designing ethical studies that protect our volunteers while still collecting scientifically useful data. 相似文献
52.
BACKGROUND: Sulphidoleukotrienes (slt) are important mediators in allergic diseases that are synthesized after allergen-specific stimulation. OBJECTIVES: The aim of this study is to determine in vitro slt production after allergen-specific (Dermatophagoides pteronyssinus) stimulus of peripheral blood leucocytes and to observe whether histamine release in whole blood with the same allergen correlates with slt production. We also wanted to evaluate whether a correlation exists between the release of slt and histamine and other diagnostic procedures as well as various clinical situations. METHODS: We studied 62 patients sensitive to Dermatophagoides pteronyssinus (Der p), 30 atopic controls and 12 healthy donors. We determined slt production using the CAST-ELISA technique and histamine release using two concentrations of Der p extract (20 and 2 ng/mL). We also carried out quantification of specific and total IgE levels, skin tests and pulmonary function test on each patient. RESULTS: We observed a significantly increased slt release after in vitro stimulation with Der p. There was a significant difference in the slt release between controls and sensitive patients (P < 0.001) and between atopic controls and sensitive patients (P < 0.001). The data are similar to those obtained with histamine release. We noted a positive correlation (P < 0.001) between slt and histamine release (r = 0.71, at 2 ng/mL and r = 0.83 at 20 ng/mL). We also found a positive (P<0.001), although weak (r=0.4 with at 2ng/mL, and r = 0.34 with P = 0.003 at 20 ng/mL) correlation between slt release and specific IgE levels as well as between slt release and skin-test reactivity (r = 0.49 at 2 ng/mL and r = 0.45 at 20 ng/mL; P < 0.001). No significant correlation between slt release and asthma severity was observed, although a trend toward higher slt production in severe and moderate asthma was detected. We found a significant (P<0.001) but weak (r=-0.3) negative correlation between age and slt release. With respect to sex-related differences, we found significant differences (P < 0.05) in slt release between the sexes with a higher slt release in men than in women. CONCLUSION: We conclude that CAST-ELISA for quantification of slt production is a useful in vitro method for diagnosing sensitization to Der p. There also exists a close correlation between slt release and other parameters of allergic sensitization in vitro as well as in vivo. 相似文献
53.
Islam S. Humail F. Akhtar S.J. Askari M. Tufail Xuanhui Qu 《International Journal of Refractory Metals and Hard Materials》2007,25(5-6):380-385
Tungsten heavy alloys (WHAs) are metal–metal composites consisting of nearly pure spherical tungsten particles embedded in a Ni–Fe–W or Ni–Co–W or Ni–Cu–W ductile matrix. In this dual phase alloy, there are several complicated relations between the ductile matrix and hard tungsten particles. The aim of this research was to examine the effect of varying tungsten content on the microstructure and mechanical properties of tungsten heavy alloys. The microstructural parameters (grain size, connectivity, contiguity and solid volume fraction) were measured and were found to have a significant effect on the mechanical properties of tungsten-based heavy alloys. The result shows that the binding strength between the W and the matrix phase has a major influence on the ductility of tungsten-based alloys. The larger this binding force is, the better the ductility is. 相似文献
54.
Other than temperature and voltage, load plays a key role in anodic bonding process. In this paper we present a new design of top electrode (cathode) for anodic bonding machine by which the bonding time has been reduced up to 30 % in case of bare silicon wafer at ?400 V and approximate 52 % in case of oxidized silicon wafer with Pyrex glass bonding at ?800 V. Experimentally it has been observed there was no bonding in oxidized silicon wafer with Pyrex glass up to ?600 V by using standard design while it has been successfully bonded at same voltage (?600 V) by using new design. 相似文献
55.
56.
Akhtar Farid GUO Shi-ju 《中国有色金属学会会刊》2006,16(3):629-632
Pressureless infiltration process to synthesize Si3N4/Al composite was investigated. Al-2%Mg alloy was infiltrated into Si3N4 and Si3N4 containing 10% Al2O3 preforms in the atmosphere of nitrogen. It is possible to infiltrate Al-2%Mg alloy in Si3N4 and Si3N4 containing 10% Al2O3 preforms. The growth of the dense composite of useful thickness was facilitated by the presence of magnesium powder at the interface and by flowing nitrogen. During infiltration Si3N4 reacted with aluminium to form Si and AIN, the growth of composite was found to proceed in two ways, depending on the Al2O3 content in the initial preform. Firstly, preform without Al2O3 content gives rise to AIN, Al3.27Si0.47 and Al type phases after infiltration. Secondly, perform with 10% Al2O3 content gives rise to AIN-Al2O3 solid solution phase (AION), MgAl2O4, Al and Si type phases. AlON phase was only present in composite, containing 10% Al2O3 in the Si3N4 preforms before infiltration. 相似文献
57.
Jianjun Tian Shengen Zhang Xuanhui Qu Farid Akhtar Siwu Tao 《Journal of Alloys and Compounds》2007,440(1-2):89-93
When sintered Sm(Co, Fe, Cu, Zr)z permanent magnets are prepared by metal injection molding, some organic binders are added in alloy powder, which leads to much residual carbon in the magnets. The residual carbon decreases magnetic properties and destroys the microstructure of the magnets. In this paper, the behavior of carbon in Sm(Co, Fe, Cu, Zr)z permanent magnets has been studied. The results indicate that Sm(Co, Fe, Cu, Zr)z magnets can keep excellent magnetic properties when the carbon content is below 0.1 wt.%: Br ≥ 10 kGs, Hcj ≥ 22 kOe, BHmax ≥ 25 MGOe. When the carbon content is above 0.1 wt.%, Br, Hcj and BHmax decrease with increasing carbon content evidently. Carbon consumes Zr content and forms ZrC, which reduces the volume fraction of the lamella and Sm(Co, Cu)5 phases. Thus, the cell size increases and the cellular microstructure deteriorates. When the carbon content reaches 0.43 wt.%, there is not enough Sm(Co, Cu)5 phase to form a uniform cellular microstructure. Br, Hcj and BHmax are approximate to zero. Since carbon has little influence on the content of Sm2(Co, Fe)17 phase, Ms can keep a high value (≥100 emu/g). ZrC has high melting point (3420 °C) and acts as dispersion particle in the magnets, which prevents the grains of SEM structure growing and reduces the liquid content of green compacts during sintering. Therefore, the density of the magnets decreases. 相似文献
58.
59.
Sania Naz Javeed Akhtar Muhammad Fayyaz Chaudhary Muhammad Zia 《IET nanobiotechnology / IET》2018,12(7):968
In this work, the authors report a facile low‐temperature wet‐chemical route to prepare morphology‐tailored hierarchical structures (HS) of copper oxide. The preparation of copper oxide collides was carried out using varying concentrations of copper acetate and a reducing agent at a constant temperature of 50°C. The prepared HS of CuO were characterised by powdered X‐rays diffraction that indicates phase pure having monoclinic structures. The morphology was further confirmed by field‐emission scanning electron microscope. It reveals a difference in shape and size of copper oxide HS by changing the concentration of reactants. In order to evaluate the effect of H2 O2 on CuO NPs, the prepared CuO are modified by treatment with H2 O2. In general trend, CuOH2 O2 collide showed enhanced protein kinase inhibition, antibacterial (maximum zone 16.34 mm against Staphylococcus aureus) and antifungal activities in comparison to unmodified CuO collides. These results reveal that CuO HS exhibit antimicrobial properties and can be used as a potential candidate in pharmaceutical industries.Inspec keywords: molecular biophysics, antibacterial activity, X‐ray diffraction, microorganisms, copper compounds, nanofabrication, nanoparticles, narrow band gap semiconductors, field emission scanning electron microscopy, enzymes, nanomedicine, particle size, semiconductor growthOther keywords: unmodified CuO collides, low‐temperature synthesis, morphology‐tailored hierarchical structures, copper acetate, reducing agent, monoclinic structures, copper oxide HS, CuO NPs, Staphylococcus aureus, biological activity, copper oxide, powdered X‐ray diffraction, field‐emission scanning electron microscopy, facile low‐temperature wet‐chemical method, protein kinase inhibition, antibacterial activity, antifungal activity, antimicrobial properties, pharmaceutical industries, temperature 50.0 degC, CuO 相似文献
60.