Glass laboratory water stills: Design and performance part B: Performance

Summary The need for simple reproducible water still performance tests is outlined briefly. Five simple tests based on sodium chloride, hydrochloric acid, ammonia, dibutylamine, and carbon dioxide are described. The methods employ an uncomplicated measurement of distillate electrical conductance. The significance of each of the five tests is discussed in terms of still design and operation. Future parts of this series will broaden the variety of performance tests to include, among other things, water impurities which are highly surface-active.     

Sinusoidal tide models: Design,construction and laboratory performance

The laboratory performance of sinusoidal tide models is discussed in relation to their construction and use. Constant-flow sinusoidal models are discussed in detail and a formula is derived to described their maximal rate of change of water-level, which is shown to occur at mid-tide. This maximum rate of change is directly proportional to the tidal amplitude and inversely proportional to the tidal period. It is shown that the maximal rate of change of water-level is limiting in the construction of tide models because it governs the rates of inflow and outflow of sea water. The inflow rate must be sufficiently great to keep up with changes in the level of the outflow pipe as it rotate. The outlet pipe, however, must be sufficiently large to remove water at an adequate rate during the ebb of the tide.     

A process-orientated design and performance assessment methodology for passive mine water treatment systems

The aim of this paper is the development of a methodology for assessing the iron removal efficiency of passive mine water treatment settling lagoons and reed beds. Previous work in the design and sizing of coal mine drainage lagoons and wetlands has focussed on the use of standard hydraulic residence times or using the 10 g m⁻² d⁻¹ metric, these criteria have been applied without regard to the fundamental physical and chemical processes controlling iron removal in the system, namely the pH dependent rates of Fe(II) oxidation and physical settling of the particulate Fe(III). In this study field water quality data have been collected from lagoons and reed beds. These data are examined alongside data from the UK Coal Authority database and combined with simple mathematical formulations to provide a framework through which to understand passive treatment schemes from a process-orientated perspective. It is demonstrated that for the sites studied reed beds are more efficient for iron removal. This paper recommends that judgements of iron removal performance should be based on a derived treatment efficiency index (?) and that the modelling approach espoused in this paper should be used when designing passive mine water treatment schemes.     

Distribution of bacteria within operating laboratory water purification systems.

Experiments were conducted to measure communities of bacteria within operating ultrapure water treatment systems intended for laboratory use. Samples from various locations within Milli-Q Plus and Milli-Q UV Plus systems were analyzed for populations of planktonic bacteria at weekly intervals over 3 months of operation. Relatively high initial densities of planktonic bacteria (10(2) to 10(3) bacteria per ml) were seen within both units when they were challenged with source water of poor quality, although the product water continued to be acceptable with regard to bacterial numbers, resistivity, and endotoxin concentration. Under more normal operating conditions, significant differences were seen in planktonic populations throughout the systems with excellent product water quality. A great deal of variability was observed in biofilm populations analyzed from various system surfaces after 3 months of operation. The concentrations of planktonic bacteria and biofilm densities were much lower in the unit containing a UV lamp. These findings suggest that a range of microenvironmental conditions exist within purified water systems, leading to variable populations of bacteria. However, product water of excellent quality was obtained despite the bacterial communities.     

Neisseria meningitidis serogroup B: laboratory correlates of protection

Meningococcal disease in the Western countries is frequently caused by Neisseria meningitidis serogroup B. Major efforts have been made to develop a safe and efficacious vaccine against this serogroup which is suitable for use in infants and young children. To assess the quality of the immune response after vaccination with candidate vaccines, laboratory correlates of protection are needed. For serogroups A and C, serum bactericidal activity (SBA) is a well established predictor for protection, but for serogroup B other mechanisms besides SBA may also be involved in conferring protection from disease. Several laboratory methods for identification and evaluation of the immunogenicity of possible vaccine antigens are described in this review.     

Cyclic and linear bradykinin analogues: implications for B2 antagonist design.

Bradykinin (BK, Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) antagonists are potentially useful for treating inflammation, pain and severe trauma. To identify what chemical features might promote effective antagonism, we replaced Arg1 and Pro7 with structurally constrained and proteolytic-resistant residues, such as Bip (biphenylalanine), Dip (diphenylalanine) or 2Ind (indane amino acid). To determine which BK folding might lead to favourable interactions with receptors, the effects of cyclo(3,8) vs. cyclo(5,8) analogues were compared. The resulting BK analogues were examined for their agonistic and antagonistic activities in guinea pig ileum, rat uterus and depressor assays. The results suggest that co-planarity of the residue-7 side chain with its backbone NH is important for potent agonism as well as antagonism, and a D-directed side chain is crucial for antagonism. For residue-1 an L-orientation is important, and Dip1 may mimic a folded Arg1 side chain to elicit agonistic activities, with Bip1 mimicking an extended Arg1 side chain to elicit inhibitory activities. However, ileal and uterine receptors appear to prefer differently folded BK. For ileum, a BK conformation in which residues-3 and -8 are proximal to each other, but apart from residue-5, led to improved pA2.     

The scope for improving the design of laboratory animal experiments.

The factors which need to be taken into account in designing a 'good' experiment are reviewed. Such an experiment should be unbiased, have high precision, a wide range of applicability, it should be simple, and there should be a means of quantifying uncertainty (Cox 1958). The relative precision due to the use of randomized block designs was found to range from 96% to 543% in 5 experiments involving 30 variables. However, a survey of 78 papers published in two toxicology journals showed that such designs were hardly used. Similarly, designs in which more than one factor was varied simultaneously ('factorial designs') were only used in 9% of studies, though interactions between variables such as dose and strain of animal may be common, so that single factor experiments could be misleading. The consequences of increased within-group variability due to infection and genetic segregation were quantified using data published by G?rtner (1990). Both substantially reduced precision, but toxicologists continue to use non-isogenic laboratory animals, leading to experiments with a lower level of precision than is necessary. It is concluded that there is scope for improving the design of animal experiments, which could lead to a reduction in animal use. People using animals should be required to take formal training courses which include sessions on experimental design in order to minimize animal use and to increase experimental efficiency.     

Earthquakes and building design: a primer for the laboratory animal professional

Earthquakes can occur in most regions of the United States, so it might be necessary to reinforce vulnerable animal facilities to better protect research animals during these unpredictable events. A risk analysis should include an evaluation of the seismic hazard risk at the proposed building site balanced against the estimated consequences of losses. Risk analysis can help in better justifying and recommending to building owners the costs of incorporating additional seismic reinforcements. The planning team needs to specify the level of post-earthquake building function that is desired in the facility, and then design the facility to it.     

A simple cardiovascular system simulator: design and performance

A simple simulator has been constructed, evaluated and used for performance studies of prosthetic aortic valves, balloon assist devices and Koroktof sounds and ausculatory cuff blood pressure measurements. A direct drive piston pump is used. Elastic soft rubber tubes with distributed resistances allow modeling of normal and diseased pressure pulse waves. Pressure pulse amplitude amplification is modeled with tube segments of decreasing diameters. Satisfactory proximal pressure pulse shapes are obtained with a soft rubber tube of uniform diameter.     

Inactivation of coxsackieviruses B3 and B5 in water by chlorine.

The inactivation rates of coxsackievirus B3 (CB3) and B5 (CB5) by chlorine in dilute buffer at pH 6 were very nearly the same and about half that of poliovirus (Mahoney) under similar conditions. Purified CB3, like the poliovirus, aggregated in the acid range but not at pH 7 and above. Purified CB5 aggregated rapidly at all pH values; still, the graph of log surviving infectivity versus time was a straight line. No chlorine inactivation data were obtained with dispersed CB5, for it could be dispersed only by addition of diethylaminoethyl dextran, which would react with the chlorine. Addition of 0.1 M NaCl to the buffer at pH 6 did not influence the aggregation of CB5 or the rate of chlorine action on either of the coxsackie-viruses, but at pH 10 it increased the disinfection activity of OCl- for both viruses roughly 20-fold. Cesium chloride had a similar but smaller effect. KCl was the most active of the three in this respect, making the inactivating effect of OCl- at pH 10 about equal to that of HOCl at pH 6.     

管道式光生物反应器的设计和性能

该文概述了管道式光生物反应器在设计上对性能的要求,对影响光生物反应器培养效率的各种生长条件如光能利用效率、CO2利用效率、环境温度、溶解氧等问题进行了探讨,指出高效并可自动调节的藻液循环混合系统对于高密度海藻培养是非常重要的,提出了能否自动清洗光生物反应器内壁是判断光生物反应器是否可用于工业化生产的关键。     

Screening for group B streptococcus: a private laboratory experience

We examined group B streptococcus (GBS) isolates colonizing women at the 35-37 weeks of pregnancy. A total of 257 group B streptococcus (GBS) isolates for serotyped using direct agglutination with a set of commercially available antisera (Ia, Ib, II, III, IV, and V) and tested for susceptibility to antimicrobials (penicillin, macrolides, lincosamides, fluoroquinolones and tetracyclines). Fourteen isolates could not be serotyped with the antisera set used in the study. Serotype III was the predominant serotype (33%), followed by serotypes V (23%), and Ia (20%). Whereas all isolates were susceptible to penicillin, the rates of susceptibility to the other antimicrobials tested were the following: 91% for ofloxacin, 80% for clindamycin, 77% for erythromycin, and 4% for tetracycline. More than half (67%) of the macrolide resistant isolates belonged to serotypes V and III. A systematic surveillance of the autochthonous GBS serotypes, performed at the level of laboratories processing a high number of human specimens, is mandatory for strengthening the national epidemiological GBS surveillance. While penicillin remains the drug of choice for intrapartum prophylaxis, the resistance of autochthonous GBS isolates to other antibiotics should be actively monitored.     

Autoreactivity by design: innate B and T lymphocytes

Innate B and T lymphocytes are a subset of lymphocytes that express a restricted set of semi-invariant, germ-line-encoded, autoreactive antigen receptors. Although they have long been set apart from mainstream immunological thought, they now seem to represent a distinct immune-recognition strategy that targets conserved stress-induced self-structures, rather than variable foreign antigens. Innate lymphocytes regulate a range of infectious, tumour and autoimmune conditions. New studies have shed light on the principles and mechanisms that drive their unique development and function, and show their resemblance to another subset of innate lymphocytes, the natural killer cells.