Investigation of doped-gadolinium zirconate nanomaterials for high-temperature hydrogen sensor applications

The incorporation of selective nanomaterials, such as common metal oxide semiconductor compositions, into resistive-type gas sensors has been shown by many researchers to lead to very high sensitivities and response rates, especially for micro-sized chemical sensors for room-temperature applications. The same strategy utilizing sensing nanomaterials has not been demonstrated for high-temperature sensors due to the intrinsic instability of typical metal oxide semiconductor nanomaterials at temperatures >500 °C. Within this work, doped Gd₂Zr₂O₇ (GZO) nanomaterial compositions were investigated for H₂ resistive-type sensors for applications between 600 and 1000 °C. This paper investigates the mechanism of H₂ sensing for doped GZO nanomaterials and SnO₂/GZO nanocomposites at the elevated temperatures. By integrating 10 vol.% nano-SnO₂ into yttrium-doped GZO nanomaterials, a sensitivity of 4.15 % was retained for 4000 ppm H₂ levels with a low signal drift of 0.42 %/h at 1000 °C in a 20 % O₂/N₂ gas stream. The signal drift was reduced by more than half of that compared to pure nano-SnO₂ at the same conditions. The nano-GZO limited the grain growth of the nano-SnO₂ particles and also prevented the nano-SnO₂ from fully reducing to Sn at high temperatures in a low oxygen atmosphere. It is among the first resistive-type sensors operating at 1000 °C with sensing times of <5 min. This demonstration provided an example of a strategy of combining traditional metal oxide semiconductor and refractory nanomaterial compositions to form sensing nanocomposites with new sensing mechanisms, as well as, enhanced chemical and microstructural stabilities in high-temperature environments.     

SeDeM expert system a new innovator tool to develop pharmaceutical forms

Context: The SeDeM expert system is based on the experimental study and quantitative determination of the characterization parameters of powdered substances, the aim being to determine whether a substance is suitable for producing tablets by means of direct compression (DC) technology, thereby reducing the lead time for pre-formulation studies. Additionally, this expert system also provides formulations with a minimum number of excipients.

Objective: We used this system to analyze suitable formulas for the production of orodispersible ibuprofen tablets.

Method: Twenty-one disintegrants and ibuprophen were characterized using SeDeM methodology.

Results: The results indicated that production of ibuprofen tablets by DC would require improvements in the dimension and compressibility factors of the active pharmaceutical ingredient. The expert system analysis provided the specific percentage of disintegrant needed to blend with ibuprofen and a standardized formula of lubricants in order to obtain a powder mix that would successfully produce tablets by DC. The eight formulas proposed by SeDeM were produced and tested in the laboratory.

Conclusion: All eight formulas successfully produced tablets by DC, but only four of them could be considered suitable for use as an orodispersible tablet and accomplishes all the pharmaceutical quality parameters. So, in fact, the use of the SeDeM system reduced the time of medicine’s development and therefore the cost of the activity.     

Greenhouse gas footprints of different biofuel production systems

The aim of this study is to show the impact of different assumptions and methodological choices on the life-cycle greenhouse gas (GHG) performance of biofuels by providing the results for different key parameters on a consistent basis. These include co-products allocation or system expansion, N₂O emissions from crop cultivation, conversion systems and co-product applications and direct land-use change emissions. The results show that the GHG performance of biofuels varies depending on the method applied and the system boundaries selected. Key factors include selected allocation procedures and the location of production and related yields, reference land and soil N₂O emissions.     

Attention as inference: Selection is probabilistic; responses are all-or-none samples.

Theories of probabilistic cognition postulate that internal representations are made up of multiple simultaneously held hypotheses, each with its own probability of being correct (henceforth, “probability distributions”). However, subjects make discrete responses and report the phenomenal contents of their mind to be all-or-none states rather than graded probabilities. How can these 2 positions be reconciled? Selective attention tasks, such as those used to study crowding, the attentional blink, rapid serial visual presentation, and so forth, were recast as probabilistic inference problems and used to assess how graded, probabilistic representations may produce discrete subjective states. The authors asked subjects to make multiple guesses per trial and used 2nd-order statistics to show that (a) visual selective attention operates in a graded fashion in time and space, selecting multiple targets to varying degrees on any given trial; and (b) responses are generated by a process of sampling from the probabilistic states that result from graded selection. The authors concluded that although people represent probability distributions, their discrete responses and conscious states are products of a process that samples from these probabilistic representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Passivation of metal alloys using sol–gel-derived materials — a review

The sol–gel method is being investigated as an environmentally compliant alternative for chromate-based conversion coatings currently in use. An overview of recent advances in the use of sol–gel derived coatings for improved corrosion resistance of aluminum and steel metal surfaces is given.     

Modification of ASTM E 2187 for Measuring the Ignition Propensity of Conventional Cigarettes

Current existing and proposed US flammability standards for soft furnishings such as mattresses and upholstered furniture specify a ??standard?? cigarette as the ignition source in smoldering resistance performance tests. With the increasing prevalence of reduced ignition propensity cigarettes in the marketplace, the conventional cigarette that has been most widely used in smolder resistance testing is no longer in production. To support manufacturers and testing organizations in product design and testing, and to assist regulators in the compliance evaluation process, a continuing supply of standard conventional cigarettes is required. A key first step in establishing such a supply is the development of a measurement method for quantifying the ignition propensity of a standard cigarette similar to the one currently used for testing soft furnishings. This article describes such a measurement method. It also reports performance data for the conventional test cigarette and other contemporary cigarettes.     

Neural correlates of individual differences in strategic retrieval processing.

Processes engaged when information is encoded into memory are an important determinant of whether that information will be recovered subsequently. Also influential, however, are processes engaged at the time of retrieval, and these were investigated here by using event-related potentials (ERPs) to measure a specific class of retrieval operations. These operations were revealed by contrasts between ERPs elicited by new (unstudied) test items in distinct tasks, the assumption being that these contrasts index operations that are engaged in service of retrieval and that vary according to the demands of different retrieval tasks. Specific functional accounts of this class of retrieval processing operations assume that they influence the accuracy of memory judgments, and this experiment was designed to test for the first time whether this is in fact the case. Toward this end, participants completed 2 retrieval tasks while ERPs were acquired, and the extent to which processes were engaged differentially across tasks in service of retrieval was operationalized as the magnitude of the differences between the new-item ERPs that were elicited. This measure correlated positively with response accuracy on the tasks, which provides strong evidence that this class of retrieval processing operations benefits the accuracy of memory judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)