Preparation of small silicon carbide quantum dots by wet chemical etching

Fabrication of nanosized silicon carbide (SiC) crystals is a crucial step in many biomedical applications. Here we report an effective fabrication method of SiC nanocrystals based on simple electroless wet chemical etching of crystalline cubic SiC. Comparing an open reaction system with a closed reaction chamber, we found that the latter produces smaller nanoparticles (less than 8 nm diameter) with higher yield. Our samples show strong violet-blue emission in the 410–450 nm region depending on the solvents used and the size. Infrared measurements unraveled that the surface of the fabricated nanoparticles is rich in oxidized carbon. This may open an opportunity to use standard chemistry methods for further biological functionalization of such nanoparticles

Perceptual narrowing in speech and face recognition : evidence for intra-individual cross-domain relations

During the first year of life, infants undergo perceptual narrowing in the domains of speech and face perception. This is typically characterized by improvements in infants' abilities in discriminating among stimuli of familiar types, such as native speech tones and same-race faces. Simultaneously, infants begin to decline in their ability to discriminate among stimuli of types with which they have little experience, such as non-native tones and other-race faces. The similarity in time-frames during which perceptual narrowing seems to occur in the domains of speech and face perception has led some researchers to hypothesize that the perceptual narrowing in these domains could be driven by shared domain-general processes. To explore this hypothesis, we tested 53 Caucasian 9-month-old infants from monolingual German households on their ability to discriminate among non-native Cantonese speech tones, as well among same-race German faces and other-race Chinese faces. We tested the infants using an infant-controlled habituation-dishabituation paradigm, with infants' preferences for looking at novel stimuli versus the habituated stimuli (dishabituation scores) acting as indicators of discrimination ability. As expected for their age, infants were able to discriminate between same-race faces, but not between other-race faces or non-native speech tones. Most interestingly, we found that infants' dishabituation scores for the non-native speech tones and other-race faces showed significant positive correlations, while the dishabituation scores for non-native speech tones and same-race faces did not. These results therefore support the hypothesis that shared domain-general mechanisms may drive perceptual narrowing in the domains of speech and face perception

Perceptual narrowing in speech and face recognition : evidence for intra-individual cross-domain relations

During the first year of life, infants undergo perceptual narrowing in the domains of speech and face perception. This is typically characterized by improvements in infants' abilities in discriminating among stimuli of familiar types, such as native speech tones and same-race faces. Simultaneously, infants begin to decline in their ability to discriminate among stimuli of types with which they have little experience, such as non-native tones and other-race faces. The similarity in time-frames during which perceptual narrowing seems to occur in the domains of speech and face perception has led some researchers to hypothesize that the perceptual narrowing in these domains could be driven by shared domain-general processes. To explore this hypothesis, we tested 53 Caucasian 9-month-old infants from monolingual German households on their ability to discriminate among non-native Cantonese speech tones, as well among same-race German faces and other-race Chinese faces. We tested the infants using an infant-controlled habituation-dishabituation paradigm, with infants' preferences for looking at novel stimuli versus the habituated stimuli (dishabituation scores) acting as indicators of discrimination ability. As expected for their age, infants were able to discriminate between same-race faces, but not between other-race faces or non-native speech tones. Most interestingly, we found that infants' dishabituation scores for the non-native speech tones and other-race faces showed significant positive correlations, while the dishabituation scores for non-native speech tones and same-race faces did not. These results therefore support the hypothesis that shared domain-general mechanisms may drive perceptual narrowing in the domains of speech and face perception

Perceptual reorganization of lexical tones : effects of age and experimental procedure

Findings on the perceptual reorganization of lexical tones are mixed. Some studies report good tone discrimination abilities for all tested age groups, others report decreased or enhanced discrimination with increasing age, and still others report U-shaped developmental curves. Since prior studies have used a wide range of contrasts and experimental procedures, it is unclear how specific task requirements interact with discrimination abilities at different ages. In the present work, we tested German and Cantonese adults on their discrimination of Cantonese lexical tones, as well as German-learning infants between 6 and 18 months of age on their discrimination of two specific Cantonese tones using two different types of experimental procedures. The adult experiment showed that German native speakers can discriminate between lexical tones, but native Cantonese speakers show significantly better performance. The results from German-learning infants suggest that 6-and 18-month-olds discriminate tones, while 9-month-olds do not, supporting a U-shaped developmental curve. Furthermore, our results revealed an effect of methodology, with good discrimination performance at 6 months after habituation but not after familiarization. These results support three main conclusions. First, habituation can be a more sensitive procedure for measuring infants' discrimination than familiarization. Second, the previous finding of a U-shaped curve in the discrimination of lexical tones is further supported. Third, discrimination abilities at 18 months appear to reflect mature perceptual sensitivity to lexical tones, since German adults also discriminated the lexical tones with high accuracy

Unique titanium Deposits of Timan: genesis and age issues

The article critically analysesthe hypotheses about the formation, age, and sources of material of large Timan titanium deposits, which were previously considered ancient buried placers formed along the weathering crusts of the Riphean shales. We discuss an alternative hydrothermal-metamorphic hypothesis about the formation of these deposits and the source of ore material. It is established that the incoming zircon of different ages (570-3200 Ma), as well as two other geochronometers, rutile and monazite, underwent a thermal effect common for all varieties as a result of a hydrothermal process about 600 Ma ago. According to modern concepts, the closing temperature of the U-Pb system in rutile exceeds 500 °С, which suggests high-temperature conditions for the hydrothermal processing of rutile during the formation of the considered deposits in the Riphean

Влияние процесса старения на свойства дорожных битумных вяжущих, содержащих термоэластопласты и резиновую крошку, получаемую методом высокотемпературного сдвигового измельчения

The influence of the aging process on the properties of asphalt binders modified with active powder of discretely devulcanized rubber (APDDR) obtained in rotor dispersers by using the technique of high-temperature shearinduced grinding (HTSG), and other types of modifier. Comprehensive study of asphalt binders according to American Standard Super Pave showed that the use of APDDR can significantly improve not only the level of performance characteristics of asphalt concrete pavement, but the aging resistance of the material during manufacture asphalt mix that is caused as a dry way of introducing this type of modifier and its complex physicochemical properties. Conducted on Dynamic Shear Rheometer test bitumen modified crumb rubber by HTSG showed applicability APDDR particles as an effective modifier asphalt binders and asphalt coatings, designed to work in different climatic zones with the highest loads.В работе исследовано влияние процесса старения на структуру и реологические свойства дорожного битума БНД 60/90 и битумных вяжущих, модифицированных резиновой крошкой, получаемой в роторных диспергаторах методом высокотемпературного сдвигового измель-чения (ВСИ), а также другими типами модификаторов. Комплексное изучение битума и битум-ных вяжущих в соответствии с американским стандартом “SuperРave” показало, что применение данной резиновой крошки позволяет существенно повысить уровень эксплуатационных свойств асфальтобетонного покрытия. Битум, модифицированный резиновой крошкой, показывает наилучшие результаты по сравнению с другими типами модификаторов как до, так и после моделирования процесса старения

Эластичные наполнители - продукты вторичной переработки резин, получаемые методом высокотемпературного сдвигового измельчения

In this article matters of investigation of basic physical, chemical and technical properties of a product of recycling rubber by means of high-temperature shift crushing deformation are considered.В работе рассмотрены вопросы, связанные с изучением основных физико-химических и технических свойств продукта вторичной переработки резины, получаемого методом высокотемпературного сдвигового измельчения (ВСИ), на основе отработанных шин и резинотехнических изделий

Влияние фракционного состава эластичного наполнителя, полученного методом ВСИ, на свойства эластомерных материалов

Ecological and economic problems of rubber goods recycling are considered. In this paper we shall present results of research of influence rubber crumbs on technological and physico-mechanical properties of elasromeric materialsВлияние фракционного состава эластичного наполнителя, полученного методом ВСИ, на свойства эластомерных материало

Исследование эластичного наполнителя, получаемого методом высокотемепреатурного сдвигового измельчения

Possibility of using elastic filler which received of the waste of tyres by conditions of high temperatures and deformation is investigated in rubber technology. The presented part of work has been directed on studying of morphological properties elastic filler, abilities to participation in vulcanization process elastomer material, comparison given kind of filler with the products of recycling of the worn out tyres presented in the modern market.В работе рассмотрены вопросы, связанные с изучением основных физико-химических и технических свойств продукта вторичной переработки резины, получаемого методом высокотемпературного сдвигового измельчения (ВСИ), на основе отработанных шин и резинотехнических изделий