A psychophysical investigation of binary bitter-compound interactions

The aim of this study was to determine if taste interactions occur when bitter stimuli are mixed. Eight bitter stimuli were employed: denatonium benzoate (DB), quinine-HCl (QHCl), sucrose octaacetate (SOA), urea, L-tryptophan (L-trp), L-phenylalanine (L-phe), ranitidine-HCl, and Tetralone. The first experiment constructed individual psychophysical curves for each subject (n = 19) for each compound to account for individual differences in sensitivities when presenting bitter compounds in experiment 2. Correlation analysis revealed two groupings of bitter compounds at low intensity (1, L-trp, L-phe, and ranitidine; 2, SOA and QHCl), but the correlations within each group decreased as the perceived intensity increased. In experiment 2, intensity ratings and two-alternative forced-choice discrimination tasks showed that bitter compounds generally combine additively in mixture and do not show interactions with a few specific exceptions. The methods employed detected synergy among sweeteners, but could not detect synergy among these eight bitter compounds. In general, the perceived bitterness of these binary bitter-compound mixtures was an additive function of the total bitter-inducing stimuli in the mouth.

An overview of binary taste-taste interactions

The human gustatory system is capable of identifying five major taste qualities: sweet, sour, bitter, salty and savory (umami), and perhaps several sub-qualities. This is a relatively small number of qualities given the vast number and structural diversity of chemical compounds that elicit taste. When we consume a food, our taste receptor cells are activated by numerous stimuli via several transduction pathways. An important food-related taste question which remains largely unanswered is: How do taste perceptions change when multiple taste stimuli are presented together in a food or beverage rather than when presented alone? The interactions among taste compounds is a large research area that has interested electrophysiologists, psychophysicists, biochemists, and food scientists alike. On a practical level, taste interactions are important in the development and modification of foods, beverages or oral care products. Is there enhancement or suppression of intensity when adding stimuli of the same or different qualities together? Relevant psychophysical literature on taste–taste interactions along with selected psychophysical theory is reviewed. We suggest that the position of the individual taste stimuli on the concentration-intensity psychophysical curve (expansive, linear, or compressive phase of the curve) predicts important interactions when reporting enhancement or suppression of taste mixtures.

The influence of sodium salts on binary mixtures of bitter-tasting compounds

In order to study potential mixture interactions among bitter compounds, selected sodium salts were added to five compounds presented either alone or as binary bitter- ompound mixtures. Each compound was tested at a concentration that elicited ‘weak’ perceived bitterness. The bitter compounds were mixed at these concentrations to form a subset of possible binary mixtures. For comparison, the concentration of each solitary compound was doubled to measure bitterness inhibition at the higher intensity level elicited by the mixtures. The following sodium salts were tested for bitterness inhibition: 100 mM sodium chloride (salty), 100 mM sodium gluconate (salty), 100 and 20 mM monosodium glutamate (umami), and 50 mM adenosine monophosphate disodium salt (umami). Sucrose (sweet) was also employed as a bitterness suppressor. The sodium salts differentially suppressed the bitterness of compounds and their binary combinations. Although most bitter compounds were suppressed, the bitterness of tetralone was not suppressed, nor was the bitterness of the binary mixtures that contained it. In general, the percent suppression of binary mixtures of compounds was predicted by the average percent suppression of its two components. Within the constraints of the present study, the bitterness of mixtures was suppressed by sodium salts and sucrose independently, with few bitter interactions. This is consistent with observations that the bitter taste system integrates the bitterness of multi-compound solutions linearly.

Propagation characteristics of lamb waves in stringer-stiffened panels

Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the above mentioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

The utility of hypercoordination and secondary bonding for the synthesis of a binary organoelement oxo cluster

A strategy for the preparation of the otherwise difficult to obtain binary organometallic oxides containing two heavy main group elements is described and exemplified by the synthesis of [(p-MeOC₆H₄)₂Te(OSnt-Bu₂OH)₂]₂.

Improved electrical efficiency by active cooling of building integrated photovoltaic panels

The electrical efficiency of photovoltaic devices can be directly related to the temperature of the photovoltaic cells.Tn this study a BIPVT solar collector was analysed and key parameters affecting its electrical efficiency were identified.

In vitro cytotoxicity of binary TI alloys for bone implants

Interest in using titanium (Ti) alloys as load-bearing implant materials has increased due to their high strength to weight ratio, lower elastic modulus, and superior biocompatibility and enhanced corrosion resistance compared to conventional metals such as stainless steel and Co-Cr alloys. In the present study, the in vitro cytotoxicity of five binary titanium alloys, Ti15Ta, Ti15Nb, Ti15Zr, Ti15Sn and Ti15Mo, was assessed using human osteosarcoma cell line, SaOS-2 cells. The Cell proliferation and viability were determined, and cell adhesion and morphology on the surfaces of the binary Ti alloys after cell culture were observed by SEM. Results indicated that the Ti binary alloys of Ti15Ta, Ti15Nb and Ti15Zr exhibited the same level of excellent biocompatibility; Ti15Sn alloy exhibited a moderate biocompatibility while Ti15Mo alloy exhibited a moderate cytotoxicity. The SaOS-2 osteoblast-like cells had flattened and spread across the surfaces of the Ti15Ta, Ti15Nb, Ti15Zr and Ti15Sn groups; however, the cell shapes on the Ti15Mo alloy was shrinking and unhealthy. These results indicated that the Mo contents should be limited to a certain level in the design and development of new Ti alloys for implant material applications.

Beyond ‘good’ and ‘evil’: breaking down binary oppositions in holocaust representations of ‘privileged’ Jews

In 1986, Auschwitz survivor Primo Levi’s paradigmatic essay entitled ‘The Grey Zone’ highlighted the complex and sensitive issue of so-called ‘privileged’ Jews, an issue that remains at the margins of popular and academic discourse on the Holocaust. ‘Privileged’ Jews include those prisoners in the Nazi concentration camps and ghettos who held positions that gave them access to material and other benefits whilst compelling them to act in ways that have been judged both self-serving and harmful to fellow inmates. The unprecedented ethical dilemmas that confronted ‘privileged’ Jews may be viewed as exemplifying the ‘limit’ events or experiences that were characteristic of the Holocaust, situating them at the threshold of representation, understanding and judgement. Levi’s essay singles out history and film as particularly predisposed to a simplifying trend he identifies – the ‘Manichean tendency which shuns half-tints and complexities,’ and resorts to the black-and-white binary opposition(s) of ‘friend’ and ‘enemy,’‘good’ and ‘evil.’ In the case of ‘privileged’ Jews in particular, such binary oppositions would appear to be inadequate. Adopting an interdisciplinary approach that incorporates the fields of history, philosophy and literature, this paper analyses representations of ‘privileged’ Jews, particularly those prisoners of the Sonderkommandos who were forced to work in the crematoria. The paper demonstrates how easily the boundary Levi maps out for moral judgement can be crossed. It is shown that while Levi suggests judgement should be suspended when confronted with the experiences of victims in extremis, moral evaluations of ‘privileged’ Jews permeate discussions and representations of the Holocaust. When confronted with such emotionally and morally freighted issues, judgement may itself be seen as a ‘limit of representation.’