Time-convolutionless mode-coupling theory near the glass transition: Numerical solutions for the Percus-Yevick model

The full numerical solutions of the time-convolutionless modecoupling theory (TMCT) equation recently proposed by Tokuyama are compared with those of the ideal mode-coupling theory (MCT) equation based on the Percus-Yevick static structure factor for hard spheres qualitatively and quantitatively. The ergodic to non-ergodic transition at the critical volume fraction φc predicted by MCT is also shown to occur even for TMCT. Thus, φc of TMCT is shown to be much higher than that of MCT. The dynamics of coherent-intermediate scattering functions and their two-step relaxation process in a β stage are also discussed

Improved Crystalline Quality of Si\u3csub\u3e1-x\u3c/sub\u3eGe\u3csub\u3ex\u3c/sub\u3e Formed by Low-temperature Germanium Ion Implantation

Improvement of crystalline quality in Si1-xGex formed by germanium ion implantation has been found. End‐of‐range defects were drastically reduced in number by lowering the substrate temperature during implantation with doses on the order of 1016 cm−2. This improvement was confirmed by electrical characterization of p‐n junctions formed in the SiGe layer as well as by transmission electron microscopy

Zone Diagrams in Euclidean Spaces and in Other Normed Spaces

Zone diagram is a variation on the classical concept of a Voronoi diagram. Given n sites in a metric space that compete for territory, the zone diagram is an equilibrium state in the competition. Formally it is defined as a fixed point of a certain "dominance" map. Asano, Matousek, and Tokuyama proved the existence and uniqueness of a zone diagram for point sites in Euclidean plane, and Reem and Reich showed existence for two arbitrary sites in an arbitrary metric space. We establish existence and uniqueness for n disjoint compact sites in a Euclidean space of arbitrary (finite) dimension, and more generally, in a finite-dimensional normed space with a smooth and rotund norm. The proof is considerably simpler than that of Asano et al. We also provide an example of non-uniqueness for a norm that is rotund but not smooth. Finally, we prove existence and uniqueness for two point sites in the plane with a smooth (but not necessarily rotund) norm.Comment: Title page + 16 pages, 20 figure

Qubit Decoherence and Non-Markovian Dynamics at Low Temperatures via an Effective Spin-Boson Model

Quantum Brownian oscillator model (QBM), in the Fock-space representation, can be viewed as a multi-level spin-boson model. At sufficiently low temperature, the oscillator degrees of freedom are dynamically reduced to the lowest two levels and the system behaves effectively as a two-level (E2L) spin-boson model (SBM) in this limit. We discuss the physical mechanism of level reduction and analyze the behavior of E2L-SBM from the QBM solutions. The availability of close solutions for the QBM enables us to study the non-Markovian features of decoherence and leakage in a SBM in the non-perturbative regime (e.g. without invoking the Born approximation) in better details than before. Our result captures very well the characteristic non-Markovian short time low temperature behavior common in many models.Comment: 19 pages, 8 figure

Effect of temperature on rheology behaviour of banana peel pectin extracted using hot compressed water

Banana peel pectin is extracted from banana peel waste using a hot compressed water extraction (140-160°C, 5 minutes, 1.18 mm particle size). Physicochemical contents of banana peel pectin were found to be in a similar range with commercial pectin, and is comprised of moisture (7.44-8.47%), ash (3.45-4.98%), protein (1.08-1.92%), fat (0.04-3.42), carbohydrate (83-86%), total sugar (1.77-3.41%), energy (353-369 kcal/100g) and specific heat (1.42-1.62 kJ/kg°C). These contents possibly related to their flow deformation of rheological behaviour. Regression analysis displayed good agreements in all models applied, apart from the Casson Model. Flow behaviour indices, n<1 and decreasing of apparent viscosity within increasing of shear rate indicates that banana peel pectin has excellent shear thinning behaviour with a presence of yield stress

Diffusive Evolution of Stable and Metastable Phases II: Theory of Non-Equilibrium Behaviour in Colloid-Polymer Mixtures

By analytically solving some simple models of phase-ordering kinetics, we suggest a mechanism for the onset of non-equilibrium behaviour in colloid-polymer mixtures. These mixtures can function as models of atomic systems; their physics therefore impinges on many areas of thermodynamics and phase-ordering. An exact solution is found for the motion of a single, planar interface separating a growing phase of uniform high density from a supersaturated low density phase, whose diffusive depletion drives the interfacial motion. In addition, an approximate solution is found for the one-dimensional evolution of two interfaces, separated by a slab of a metastable phase at intermediate density. The theory predicts a critical supersaturation of the low-density phase, above which the two interfaces become unbound and the metastable phase grows ad infinitum. The growth of the stable phase is suppressed in this regime.Comment: 27 pages, Latex, eps

Desenvolvimento de um método por LC/MS-MS para a determinação de novas substâncias psicoativas e contaminantes de drogas em cabelo

Poster apresentado no 21º Congresso Nacional de Medicina Legal e Ciências Forenses, Lamego, 12-14 de outubro de 2023As novas substâncias psicoativas (NPS) são desenvolvidas para mimetizar os efeitos psicotrópicos das drogas clássicas, e sua presença tem vindo a aumentar no mercado de drogas. Estes compostos são facilmente acessíveis (por exemplo, online) e geralmente não são regulamentados pelas políticas internacionais de drogas. Este trabalho descreve o desenvolvimento de um método sensível e específico por LC-MS/MS para deteção de NPS e contaminantes de crack, nomeadamente: 25C-NBOMe; 25E-NBOH; 25B-Nbome; etilona, mefedrona, UR-144, JWH 073; 5F-MDMB-PINACA; 3-MeO-PCP; 5-MeO-DMT; 2C-I; 2-C-C; cetamina, 3,4-MDPHP; canabidiol; estricnina, levamisole e fenacetina. 10 mg de cabelo foram extraídos com uma solução patenteada contendo metanol, ácido fórmico e acetonitrilo, sendo em seguida submetidos a uma filtração com pressão negativa usando placa de filtragem ISOLUTEâ. A análise foi realizada no sistema SciexTriple Quad 5500 com UPLC ExionLC AD. A separação cromatográfica foi realizada a 40 ºC numa coluna Aqcuity BEH C18 2.1x50mm; 1.7 μm i.d. A fase móvel consistiu em 0,1% de ácido fórmico em água (A) e 0,1% de ácido fórmico em acetonitrilo (B), iniciando com 2% de concentração de B até 95% em 1,5min. Esta proporção foi mantida constante até 2 min e de seguida as condições iniciais do método foram reestabelecidas por mais 0,5 minutos. O tempo total de corrida foi de 2.6 minutos. Os compostos foram ionizados por eletrospray em modo positivo em modo MRM com duas transições por analito para identificar e quantificar os compostos. Os parâmetros de ionização da fonte e de fragmentação foram otimizados para obtenção dos melhores resultados. Foi obtida linearidade entre 0,1 a 1 ng/mg para todos os analitos obtendo um coeficiente de correlação superior a 0,99. Os valores ion ratio obtidos também foram satisfatórios, reforçando a confiabilidade dos dados obtidos. Ao testar o efeito matriz, observou-se que a maioria dos analitos não apresentou interferências significativas, garantindo a precisão das análises. O método descrito demonstrou ser eficaz para a deteção de NPS e contaminantes em amostras de cabelo, permitindo a identificação e quantificação precisa de vários compostos de interesse. A utilização de amostras de cabelo como matriz de análise oferece vantagens por ser menos invasiva em comparação com outras amostras biológicas tradicionais, como sangue e urina. A aplicação desse método analítico pode contribuir para aprimorar a monitorização clínica e forense de consumidores de NPS, auxiliando na tomada de decisões relacionadas com a saúde pública e com o controlo de drogas. A crescente preocupação com o uso de NPS exige o contínuo desenvolvimento de métodos analíticos eficazes para enfrentar os desafios emergentes no campo da toxicologia.N/

Circulating Levels of Resistin and Risk of Type 2 Diabetes in Men and Women: Results From Two Prospective Cohorts

OBJECTIVE—The purpose of this study was to investigate the role of circulating resistin levels in the development of type 2 diabetes using two prospective cohorts of well-characterized men and women