The interaction of imposed and inherent olfactory mucosal activity patterns and their composite representation in a mammalian species using voltage-sensitive dyes

From amphibian data, two mechanisms that could underlie the encoding of odorants by the mucosal activity patterns they engender are as follows (1) receptors with similar odorant selectivities could be aggregated spatially on the mucosa (inherent patterns); (2) in analogy to gas chromatography, as odorants are drawn along the surface of the mucosa the strongly sorbed ones could be deposited preferentially upstream, whereas the weakly sorbed ones could be distributed more evenly (imposed patterns). Do both of these possible coding mechanisms operate in mammals and, if so, how do they interact in giving composite patterns (imposed + inherent)? Fluorescence changes in di-4-ANEPPS applied to rat mucosas were monitored by a 10 x 10 pixel photodiode array. To observe the inherent patterns, three odorants of varying sorbabilities first were puffed uniformly onto the entire mucosa mounted in a Delrin chamber. To bring out the imposed patterns, the chamber was then sealed to replicate anatomically the rat's nasal cavity, and these same odorants were drawn at three flow rates along the mucosal flow path. The results demonstrated for the first time the existence of imposed patterns in a mammal. The strongly sorbed odorants, unlike the weakly sorbed one, showed marked imposed patterns. Within physiological limits, increasing the flow rate decreased the magnitude of the imposed patterns. One might consider strategies that the olfactory process could use either to negate or to take advantage of the chromatographic effect, because the lability of the composite patterns with changing stimulus conditions raises questions about their role in odorant encoding.     

The Ile164 beta2-adrenergic receptor polymorphism adversely affects the outcome of congestive heart failure

The beta2-adrenergic receptor (beta2AR), an important modulator of cardiac inotropy and chronotropy, has significant genetic heterogeneity in the population. Because dysfunctional betaARs play a role in the pathogenesis of the failing ventricle, we tested the hypothesis that beta2AR polymorphisms alter the outcome of congestive heart failure. 259 patients with NYHA functional class II-IV heart failure due to ischemic or dilated cardiomyopathy were genotyped and prospectively followed, with the endpoint defined as death or cardiac transplantation. The allele frequencies between this group and those of 212 healthy controls also were compared and did not differ between the groups. However, those with the Ile164 polymorphism displayed a striking difference in survival with a relative risk of death or cardiac transplant of 4.81 (P < 0.001) compared with those with the wild-type Thr at this position. Age, race, gender, functional class, etiology, ejection fraction, and medication use did not differ between these individuals and those with the wild-type beta2AR, and thus the beta2AR genotype at position 164 was the only clear distinguishing feature between the two groups. The 1-yr survival for Ile164 patients was 42% compared with 76% for patients harboring wild-type beta2AR. In contrast, polymorphisms at amino acid positions 16 (Arg or Gly) or 27 (Gln or Glu), which also alter receptor phenotype, did not appear to have an influence on the course of heart failure. Taken together with cell-based and transgenic mouse results, this study establishes a paradigm whereby genetic variants of key signaling elements can have pathophysiologic consequences within the context of a disease. Furthermore, patients with the Ile164 polymorphism and heart failure may be candidates for earlier aggressive intervention or cardiac transplantation.     

Hydrostatic and uniaxial pressure effect on Tc of YBa2Cu3Ox

The Variation of the transition temperature T_c of YBa₂Cu₃O_x with hydrostatic He-gas pressure depends on the oxygen content x. The pressure effect dT_c/dp increases from small negative values at x=7 to dT_c/dp=7.4 K/GPa at x=6.7. For oxygen contents below x=6.7 dT_c/dp drops to 3 K/GPa and remains nearly constant¹. The charge transfer model² cannot explain the drop at x=6.7.Thermal expansion measurements on YBa₂Cu₃O_x indicated that the uniaxial pressure effects along the three crystal axes are different^3,4 To investigate the uniaxial pressure effects inductively an experimental setup was constructed. The T_c-change of several YBa₂Cu₃O_x single crystals with different oxygen contents has been investigated under pressure along the c-axis. To avoid oxygen ordering processes the samples were held below 105 K during the measurements. The results of uniaxial pressure measurements in c-axis direction fit to former uniaxial pressure data^3,4,5 and are explained within the charge transfer model. Hydrostatic pressure data¹² of overdoped samples fit to the same curve. However, this is not the case for underdoped samples. From this we conclude that only a part of the hydrostatic pressure effect can be explained by charge transfer in the underdoped region. The remaining part can be ascribed to uniaxial pressure effects along the a- and b-axis.     

Ion formation by high velocity impacts on porous metal targets

In impact ionization studies the target normally consists of a metal surface of compact solid density. In the present experiments, we investigate the use of a layer of a highly porous structure of nanometre-sized grains, sometimes also called “metal black”, as an alternative target. In our comparative experiments, spherical iron particles (0.1<d_p<1.5 μm) were shot with velocities 2–30 km/s onto both a compact solid silver plate and a silver metal black layer of about 7 μm thickness (grain size 20–40 nm, mean density ≈1 g/cm³), deposited on a compact solid gold plate. Impact generated ions were analysed by means of time-of-flight mass spectrometry. The results reveal important advantages of the porous black layer, such as better mass resolution and a larger amount of ions from the impacting particle. Therefore metal blacks may be very suitable targets for the purposes of identification and characterisation of the impacting particle's composition. An attempt is made to give a physical explanation of the results in the frame of existing empirical ionization models. The study is part of a programme to improve devices for in-situ analysis of fast moving cosmic dust particles.     

Rapid detection of the Chlamydiaceae and other families in the order Chlamydiales: three PCR tests

Few identification methods will rapidly or specifically detect all bacteria in the order Chlamydiales, family Chlamydiaceae. In this study, three PCR tests based on sequence data from over 48 chlamydial strains were developed for identification of these bacteria. Two tests exclusively recognized the Chlamydiaceae: a multiplex test targeting the ompA gene and the rRNA intergenic spacer and a TaqMan test targeting the 23S ribosomal DNA. The multiplex test was able to detect as few as 200 inclusion-forming units (IFU), while the TaqMan test could detect 2 IFU. The amplicons produced in these tests ranged from 132 to 320 bp in length. The third test, targeting the 23S rRNA gene, produced a 600-bp amplicon from strains belonging to several families in the order Chlamydiales. Direct sequence analysis of this amplicon has facilitated the identification of new chlamydial strains. These three tests permit ready identification of chlamydiae for diagnostic and epidemiologic study. The specificity of these tests indicates that they might also be used to identify chlamydiae without culture or isolation.     

用于汽车轻量化的结构粘接

人们对车辆的需求趋向于安全性更强、质量更轻且燃料利用效率更高等方面，因此，一种采用了先进高强度钢材、工程塑料及轻质金属的轻型车体结构也随之打入市场。如果单独使用上述材料（先进高强度钢材、工程塑料及轻质金属），就会对最大限度减轻车体质量的潜能造成限制，一种化学基材的结构粘合剂和结构泡沫塑料的应用，巧妙地将上述3种减轻车体质量的方法结合在一起，克服了安全性、质量和加工成本高等难题。     

Sequential flow process for the controlled polymerisation and thermolysis of RAFT-synthesised polymers

The RAFT (Reversible Addition-Fragmentation Chain Transfer) process greatly enhances the control over radical polymerisations, while leaving behind a thiocarbonylthio end-group. Thermolysis presents a convenient and efficient way of removing the thiocarbonylthio end-group from RAFT polymers, without the use of additional reagents. This paper describes a simple two-step flow process for the synthesis of RAFT polymers followed by the subsequent removal of the RAFT end-group via thermolysis, without the need for isolating intermediates. A range of different polymers based on styrene, acrylates, methacrylates and acrylamides were synthesised with different RAFT agents and successfully tested for thermolysis at temperatures between 220 and 250 °C in a stainless steel tube flow reactor, resulting in complete removal of thiocarbonylthio end-groups.