Designing optical glasses by machine learning coupled with a genetic algorithm

Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (T_g) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (n_d) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high n_d (1.7 or more) and low T_g (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.     

Evaluation of environmental levels and biological impact of TBT in Malta (central Mediterranean)

Chemical monitoring for butyltins in bulk seawater, surface microlayer and superficial sediments determined that the two main local sources of marine contamination by tributyltin (TBT) compounds in Malta are ship-repairing dockyards and marinas. In bulk seawater, TBT values ranged from below the detection limit of 5 ng Sn l(-1) to 300 ng Sn l(-1); in sediments derived from the most polluted areas, TBT concentrations as high as 1500 ng Sn g(-1) were measured. At TBT levels found in local harbours, several sublethal biological responses are possible and were observed, including a significant reduction in MFO enzyme system activities of fish; digestive cell atrophy in the oyster Ostrea edulis; and induction of imposex in the snail Hexaplex trunculus. The latter two responses are evident at TBT concentrations below the environmental quality standard (20 ng TBT l(-1)). The ecological implications of these results are discussed and it is concluded that exposure of marine organisms to TBT in local harbours may be expected to lead to a reduction in the long-term survival of a number of such organisms. For these reasons, both the use of TBT-based antifouling paints for pleasure boats as well as drydock practices need to be controlled by appropriate regulations and their enforcement.     

Micro-abrasion wear testing of triode plasma diffusion and duplex treated Ti–6Al–4V alloy

In this paper micro-abrasion wear testing is used to evaluate the wear resistance of triode plasma diffusion-treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex-diffusion and coated Ti–6Al–4V under uniform three-body rolling abrasion. Nanoindentation, Knoop microhardness, mechanical surface profilometry, optical microscopy, scanning electron microscopy and atomic force microscopy, were used to characterise the surfaces under investigation. Optimum testing conditions for rolling abrasion were established by varying the test parameters and resultant severity of contact. Very low normal loads and high volume fractions of particles in the abrasive slurry are necessary to obtain predictable and reproducible results. Relatively coarse SiC abrasive particles, having a mean diameter of around 3 μm, appear more suitable for micro-abrasion testing of the samples investigated, compared to finer Al₂O₃ particles. Problems associated with the measurement of the scar volume and subsequent calculation of the wear rate for hard coatings deposited on relatively soft metals like titanium are identified, and suitable testing and measurement techniques are suggested. Three-dimensional wear scar maps generated by mechanical stylus profilometry were used to measure the wear volumes. Under the test conditions used, wear coefficients can be determined from perforating and non-perforating tests, although perforating tests provide more consistent results. Triode plasma diffusion treatments, plasma-assisted (PA) PVD TiN and PAPVD CrAlN can reduce the specific wear rate of Ti–6Al–4V, while PACVD-based WC/C coatings do not provide suitable protection against abrasive wear. The combination of triode plasma oxynitriding diffusion treatments and PVD coatings to create duplex treatments can also lead to further reductions in the coating wear coefficient when compared to non-duplex coatings deposited on non-pretreated substrates.     

Evaluation of an intelligent seat system

This study was conducted to evaluate the effect of an intelligent seat system, a microprocessor-based interactive seat that automatically adjusts itself to fit a seated individual by making pressure-sensitive adjustments on its own. First, a standard American automobile seat ('baseline' seat) was assessed for comfort. Subjective ratings of comfort, pressure distribution and seated anthropometric measurements were recorded for 20 test subjects. These measurements were recorded while the subjects maintained a simulated driving position in a seat buck. The comfort scale was based on a rating of 1 to 10, with 1 corresponding to 'very poor' and 10 corresponding to 'very good.' Based on a nonlinear, multiple regression model that had been previously developed, the comfort rating of the seat was predicted based on the subjective ratings and the recorded values of 450 pressure measurements from 20 subjects. The predicted comfort value was 7.46 for the baseline seat. Following the baseline assessment, the intelligent seat system was installed into the standard American automobile seat. The objective and subjective assessments were then repeated for 17 subjects and the new predicted comfort rating was 8.06. A t-test performed on the subjective and objective measures indicated that this was a significant improvement in seat comfort. Overall, subjects felt the self-adjusting seat was more customized and more comfortable, providing a better fit.     

Positioning narratives of wine tourism websites: a lexical analysis across two different regions

Wine tourism is becoming an increasingly important tourism niche with various regions competing for tourism dollars. It is often assumed that differentiation in the sector is region based. This research investigates the positioning narratives from websites of a sample of top wine tour service firms across the US and Australia. Analysis is undertaken using an innovative methodology that combines computer-based lexical analysis followed by hierarchical clustering on principal components. The research seeks to determine the extent to which identified clusters are region based and whether the positioning narratives on websites can provides useful clusters across regions. Results are reported, implications are discussed, limitations are noted and possible areas for further research are indicated.     

Effect of glutamate and inosinate on sensory and instrumental texture of extruded products

Expanded products have been developed by extrusion of non-conventional highly nutritious raw materials such as amaranth and chickpea blended with bovine lung. As sensory acceptance of these snacks is restricted, this study aimed at improving their texture, through the addition of monosodium glutamate (MSG) and disodium inosinate (IMP) flavor enhancers to the feeding material, or to the flavor added after the extrusion. Sensory and mechanical analyses showed that both enhancers affected texture, assessed by sensory and instrumental methods. Addition of IMP together with MSG to the chickpea-based snacks presented the best results. This beneficial effect was not observed in the amaranth-based snack, suggesting that IMP and MSG can favorably impact texture of extruded products depending on the amount and type of protein present.     

Impact wear resistance of plasma diffusion treated and duplex treated/PVD-coated Ti-6Al-4V alloy

In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode plasma diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex diffusion treated/PVD-coated Ti-6Al-4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode plasma diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode plasma oxidation and nitriding diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either plasma diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.     

The beginnings of orthographic knowledge: Children's knowledge of double letters in words.

Three experiments were carried out to examine the development of knowledge about double letters. Children and adults chose items they thought looked most word-like from pairs of nonwords. First graders chose nonwords with final doublets (e.g., baff) and allowable doublets (e.g., yill) as more word-like than nonwords with initial doublets (e.g., bbaf) or unallowable doublets (e.g., yihh). Children in late kindergarten chose final-doublet nonwords (e.g., pess) more often than initial-doublet nonwords (e.g., ppes), but performed at chance when choosing between items such as jull and jukk . The same children in 1st grade chose jull more often than jukk even though their own spellings were semiphonetic and phonetic according to stage theories of spelling development. Only participants in the 6th grade and above knew the correspondence between a medial doublet and a preceding short vowel (e.g., tebbif). The results suggest that even young writers know about simple orthographic patterns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differentiating between parthenogenetic and "positive development" embryos in turkeys by molecular sexing

In mated or inseminated turkeys, 5 to 15% of eggs set for incubation show only rudimentary development. Most of these embryos die during the first 24 to 48 h of incubation and contain only unorganized sheets of tissue. This abnormal development is termed "positive development" (PD). Turkey eggs also show incidence of parthenogenesis and the resulting progeny is believed to be always male. As both types of embryos are morphologically similar at the early stage of incubation, it has been speculated that PD embryos may in fact be parthenogens. By identifying the sex at the blastodermal stage with the help of DNA markers, we have differentiated between the PD embryos and parthenogens. Parthenogenetic embryos were obtained from eggs laid by uninseminated or virgin Beltsville Small White (BSW) hens, and the PD embryos were obtained from eggs of inseminated Nicholas and British United Turkeys of America (BUTA) hens. DNA was extracted from blastoderms of parthenogenetic and PD embryos. Turkey W-chromosome specific DNA probe and primers were used to detect females in all samples by Southern blot and polymerase chain reaction (PCR), respectively. No female was detected among the 35 parthenogens examined, whereas there were 3 females among the 11 PD embryos. The presence of both males and females among PD embryos suggests that they are products of fertilization, and that at least these 3 female embryos, if not all the 11 PD embryos, are not of parthenogenetic origin. It is concluded, therefore, that PD embryos result from errors in fertilization or from early embryonic mortality following successful fertilization, and that they are unlikely to be of parthenogenetic origin.