The Building Blocks of Battery Technology: Using Modified Tower Block Game Sets to Explain and Aid the Understanding of Rechargeable Li-Ion Batteries.

While Li-ion batteries are abundant in everyday life from smart phones to electric vehicles, there are a lack of educational resources that can explain their operation, particularly their rechargeable nature. It is also important that any such resource can be understood by a wide range of age groups and backgrounds. To this end, we describe how modified tower block games sets, such as Jenga, can be used to explain the operation of Li-ion batteries. The sets can also be utilized to explain more advanced topics such as battery degradation and challenges with charging these batteries at high rates. In order to make the resource more inclusive, we also illustrate modifications to prepare tactile tower block sets, so that the activity is also suitable for blind and partially sighted students. Feedback from a range of groups supports the conclusion that the tower block sets are a useful tool to explain Li-ion battery concepts.

Treatment of experimental granulomatous uveitis by lipoxygenase and cyclo-oxygenase inhibitors.

Lens-induced granulomatous uveitis was produced in brown Norway rats. To determine the role of the lipoxygenase and cyclo-oxygenase products of arachidonic acid in the modulation of granulomatous uveitis, one group of experimental animals was treated with nafazatrom, while another group was treated with nordihydroguaiaretic acid (lipoxygenase inhibitors). Both resulted in significant attenuation of granulomatous inflammation, with reduced giant-cell infiltration into the choroid. In contrast, indomethacin (a cyclo-oxygenase inhibitor) therapy resulted in increased giant-cell formation. These findings suggest that the lipoxygenase and cyclo-oxygenase products of arachidonic acid play a role in the development of granulomatous uveitis and that such inflammation can be selectively suppressed by lipoxygenase inhibitors.

Respiratory activity in Listeria monocytogenes.

Listeria monocytogenes possessed glucose oxidase and NADH oxidase activities in whole cells and lysed protoplasts respectively. The NADH oxidase activity sedimented with the membrane fraction and was inhibited by the respiratory inhibitors rotenone, 2-heptyl-4-hydroxy-quinoline-N-oxide and cyanide, suggesting the presence of a membrane associated respiratory chain.

Ophthalmic complications with disseminated intravascular coagulation.

Massive lid oedema, ecchymosis, proptosis with a total restriction of extraocular movement, markedly raised intraocular pressure, and occlusion of the central retinal artery developed acutely in the right eye of a 26-year-old woman with a past history of disseminated intravascular coagulation. She had been admitted to hospital for symptoms of abdominal pain and bleeding from multiple sites a few hours earlier. Five days previously she had some proptosis of the other eye and had been treated with antibiotics for suspected orbital cellulitis at another hospital. The oedema and proptosis resolved on high-dose intravenous corticosteroid therapy. Despite attempts to relieve the orbital oedema and raised intraocular pressure with a lateral canthotomy and antiglaucoma medications, the patient lost all perception of light in the right eye and has subsequently developed an optic nerve atrophy.

Auditory frequency discrimination in patterned-sound-naive albino rats.

To test the hypothesis that prior patterned or varied auditory experience was necessary for the development of discrimination of auditory frequency, Sprague-Dawley albino rats were deprived of patterned sound from birth by the technique of rearing them in white noise. The sound-deprived rats learned a frequency discrimination as easily as controls reared in varied sound conditions.

Human sound frequency preferences.

205 subjects each chose a "most pleasant" sound delivered through an earphone by turning the control knob on a continuously variable audio oscillator. Most subjects chose a frequency in a relatively narrow (approximately 350 Hz) band centered on 399 Hz. The preferences did not appear to be influenced by sex or age.

The effect of oxygen inhalation on temporary threshold shift in humans.

To examine the effects of an increased oxygen supply on the establishment of noise-induced TTS in humans, 20 Ss were exposed for 10 min to a narrow band of noise centered at 3 kc/s at 100 db SPL, while inhaling either a 60% or a 90% oxygen-air mixture. In a control condition, these Ss inhaled air only while being subjected to the same noise. In the 10 Ss who had inhaled the 90% mixture, TTS was less than when they had inhaled air (delta TTS - 2.06 db, p less than 0.25). Delta TTS (0.07 db) for the 10 Ss who inhaled the 60% mixture was not significant. A further 5 Ss inhaled the 90% mixture for 10 min with no noise exposure; there was no effect on the hearing threshold levels. It was concluded that inhalation of at least 90% oxygen-air for 10 min does not affect HTLs but does reduce TTS. A re-examination was suggested of the possibility that there is a relationship between auditory fatigue and supply of oxygen to cochlear structures.

The apparent oxidation of NADH by whole cells of the methylotrophic bacterium Methylophilus methylotrophus. A cautionary tale.

Previous reports that whole cells of Methylophilus methylotrophus oxidase exogenous NADH have been investigated. Essentially identical rates of oxygen consumption were observed following the addition of methanol or NADH to whole cells. Both activities were inhibited by EDTA and hydroxylamine, but not by HQNO, and exhibited similar pH optima. Analyses of the reaction stoichiometry with NADH as substrate showed that the expected amount of oxygen was consumed, but also revealed acidification (instead of alkalinisation) and no oxidation of NADH. Further studies showed that commercial NADH is contaminated with ethanol which is oxidised to acetic acid by the low specificity methanol oxidase system present in this organism. The oxidation of exogenous NADH by whole cells of M. methylotrophus reported previously is therefore spurious.

Lactate and acetate production in Listeria innocua.

Listeria innocua NCTC 11289 was grown aerobically in continuous culture in defined media at 30 degrees C. Both acetate and lactate were produced, the proportion of acetate decreased with increasing dilution rate. Enzymatic analysis showed lactate dehydrogenase was activated 10-fold by fructose-1, 6-bisphosphate. The presence of phosphate acetyltransferase and acetate kinase but not pyruvate oxidase was detected, suggesting the sequential action of phosphate acetyltransferase and acetate kinase to produce acetate from acetyl CoA via acetylphosphate.

Oxygen consumption and noise-induced TTS in humans.

Young adult men (N:16) were used to examine the effects of increased oxygen availability upon noise-induced TTS. In 2 sessions a day apart, Ss inhaled either medical grade air or 100% oxygen during monaural exposure in their better ear to 10 min of narrow-band noise centered a 3 kc/s at 100 db SPL. Oxygen consumption was recorded with a respirometer during oxygen breathing. Conditions were counterbalanced among Ss. TTS2 min at 4 kc/s was significantly less with oxygen inhalation, confirming a previous study; however, no relationship was found between amount of oxygen consumed and the amount of TTS during pure oxygen inhalation.

Effect of sodium chloride on the intracellular solute pools of Listeria monocytogenes.

The concentrations of intracellular solutes in Listeria monocytogenes were examined in cells grown at various concentrations of NaCl. At 5% NaCl, cells contained elevated concentrations of potassium and glycine betaine compared with concentrations in cells grown without NaCl. At 7.5% NaCl, cells contained increased concentrations of K+, glycine betaine, glycine, alanine, and proline. Only glycine betaine, choline, or glycine promoted growth on a solidified defined medium containing 4% NaCl; there was no growth at higher concentrations of NaCl in the defined medium.

The adsorption of bacteria to immobilized lectins.

The agglutination of a selection of bacteria by some lectins was examined. The lectin from Codium fragile agglutinated seven strains of Salmonella typhimurium. The lectin from Helix pomatia agglutinated eight of 12 strains of Listeria monocytogenes and a further two strains gave a weak agglutination reaction. Helix pomatia lectin conjugated to magnetic microspheres enabled the adsorption of L. monocytogenes from suspension with subsequent elution by the competing ligand N-acetyl galactosamine. Affinity chromatography of a suspension of L. monocytogenes through a column of H. pomatia lectin immobilized on agarose, also adsorbed cells and enabled subsequent elution with N-acetyl galactosamine. The column technique enabled the more rapid adsorption of bacteria perhaps because of improved interactions between bacteria and immobilized lectin.

Transport of glycine-betaine by Listeria monocytogenes.

Uptake of [14C]glycine-betaine by Listeria monocytogenes was stimulated by NaCl with optimal stimulation at 0.4-0.5 M. The glycine-betaine transport system had a Km of 22 microM and a Vmax of 11.7 nmol-1 min-1 mg-1 protein when grown in the absence of NaCl. When grown in the presence of 0.8 M NaCl the Vmax increased to 27.0 nmol-1 min-1 mg-1 protein in 0.8 M NaCl. At NaCl concentrations above 0.5 M the uptake rate of glycine-betaine was reduced. Measurement of intracellular K+ concentrations and fluorescent dye quenching indicated that higher NaCl concentrations also led to a decrease in the electrochemical potential difference across the cytoplasmic membrane. Uptake of glycine was also observed, but this was not stimulated by NaCl.

Investigation of a simple amperometric electrode system to rapidly quantify and detect bacteria in foods.

A two electrode system mounted as a single probe was developed to measure electrochemically the rate of reduction of a redox mediator (thionine) by bacteria. The system gave a rapid (2 min) bacterial-dependent current above 2.5 x 10(5) cfu/ml with pure cultures of bacteria, but when applied to the measurement of the bacterial contamination in samples of meat and milk it was unable to detect or quantify the contamination reliably. Incubation of samples for a few hours before examination enabled the system to detect bacteria in excess of 10(6) cfu/ml.

The effect of EDTA and related chelating agents on the oxidation of methanol by the methylotrophic bacterium, Methylophilus methylotrophus.

The effects of EDTA and related metal-chelating agents on the respiratory system of the methylotrophic bacterium Methylophilus methylotrophus have been investigated. EDTA completely inhibited whole cell methanol oxidase activity and concomitantly decreased the aerobic steady-state reduction level of cytochrome c, but only partially inhibited methanol dehydrogenase activity. Analysis of the inhibition kinetics of EDTA and other chelating agents on methanol oxidase activity indicated that they were effective in the order CDTA greater than EDTA greater than HEDTA greater than EGTA greater than EDDA, and that they inhibited in an uncompetitive manner. Inhibition by EDTA varied as a function of the ambient cell mass in the assay, and could be partly reversed by the addition of divalent cations. EDTA had no effect on the activity of solubilised methanol dehydrogenase. These and other results indicate that EDTA binds a divalent metal ion, probably Mg2+, which is involved in the functional association of methanol dehydrogenase with the respiratory membrane. This concept is discussed in terms of the electron transfer properties and spatial organisation of the terminal respiratory chain of M. methylotrophus.

The use of immobilized lectins in the separation of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. from pure cultures and foods.

Lectins from Helix pomatia, Canavalia ensiformis, Agaricus bisporus and Triticum vulgaris agglutinated cultures of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. This agglutination was specific as it was inhibited (except with A. bisporus lectin) by the competing sugar substrates. The ability of three of these lectins, immobilized on a variety of supports, to separate these micro-organisms from pure cultures was investigated. Immobilization of the lectins on magnetic microspheres was the most effective method. Immobilized T. vulgaris lectin bound 87-100% of cells from cultures of L. monocytogenes, 80-100% of Staph. aureus, 33-45% of Salmonella spp. and 42-77% of E. coli. The A. bisporus lectin bound 31-63% of cells in cultures of L. monocytogenes, 83% of Staph. aureus but only 3-5% of the salmonella cells. Similarly H. pomatia lectin bound greater than 92% of Staph. aureus and 64% of L. monocytogenes cells but was poor at binding the Gram-negative organisms. This preference for binding Gram-positive organisms was confirmed when mixed cultures were studied. The T. vulgaris lectin was effective in removing L. monocytogenes (43%) and Staph. aureus (26%) from diluted milk and Salmonella (31-54%) from raw egg. Agaricus bisporus lectin removed L. monocytogenes from undiluted milk (10-47%) or ground beef (32-50%).

The effect of temperature and growth rate on the susceptibility of Listeria monocytogenes to environmental stress conditions.

The effect of growth temperature and growth rate on the susceptibility to heat and pH stress were investigated in Listeria monocytogenes grown in continuous culture where these two growth variables could be varied independently of each other, and in batch culture. After growth at 30 degrees C or 10 degrees C at constant growth rate, or at 30 degrees C at different growth rates, cells did not differ in their resistance to heat at 55 degrees C. Cells grown at 30 degrees C were more resistant to acid stress at pH 2.5 than cells grown at the same growth rates at 10 degrees C. Cells grown at low growth rate at 30 degrees C gave greater resistance to acid stress than those grown at high growth rate. Growth temperature and growth rate had independent effects on the susceptibility of L. monocytogenes to acid stress conditions. This may have implications for the survival of L. monocytogenes in acidic foods.

Use of the polymerase chain reaction and oligonucleotide probes for the rapid detection and identification of Carnobacterium species from meat.

The polymerase chain reaction (PCR) was used selectively to amplify specific rDNA sequences of Carnobacterium divergens, C. mobile, C. piscicola and C. gallinarum in purified DNA extracts, crude cell lysates and food samples. The PCR products were visualized by agarose gel electrophoresis and identified, at species level, by hybridization reactions with three specific oligonucleotide probes for C. divergens, C. mobile and C. piscicola/C. gallinarum designed from 16S rRNA sequence data. The PCR was sufficiently sensitive to amplify DNA from a single bacterium to detectable levels after 30 cycles of amplification. Both radioactive (32P) and non-radioactive alkaline phosphatase labelled probes was able to detect the PCR products. Detection was highly specific and the probes did not hybridize with DNA samples from any other of the bacterial species tested. These methods enabled the rapid and specific detection and identification of carnobacteria from pure cultures and samples of meat.