The effect of gear geometry on the thickness of tooth face hardened layer

This article describes the effect of the geometrical parameters of the standard involute and non-standard convex-concave (C-C) gearing on the thickness of the hardened layer. The thickness of hardened layer is important from the aspect of wear on gearing. In case of involute gearing is the thickness of the hardened layer defined by various authors, what is on the other hand determinated also by the standard STN 01 4686-5. In case of C-C gearing there are not available any standards, and therefore it is possible to determine the thickness of the hardened layer only by the means of modern simulation methods.В статье описывается влияние геометрических параметров стандартных эвольвентных и нестандартных выпукло-вогнутых (CC) зубчатых передач до толщины упрочненного слоя. Толщина упрочненного слоя имеет важное значение для износа зуба. В случае с эвольвентной передачей толщина слоя определяется более авторами, и также использованием стандарта STN 01 4686-5. В случае нестандартных выпукло-вогнутых (C-C) зубчатых передач нет стандартов, поэтому можно определить толщину закаленного слоя только с использованием современных методов моделирования

O MARKETING DE SERVIÇOS: Análise da Satisfação dos Clientes/Utentes da Embaixada de São Tomé e Príncipe em Portugal

No presente trabalho pretende-se, através de um projeto aplicado na área de marketing de serviços, analisar a satisfação dos utentes da Embaixada de São Tomé e Príncipe (STP) em Portugal pelos seus serviços prestados, mediante um estudo quantitativo exploratório tendo-se utilizado como instrumento de recolha de dados um questionário, constituído com base da escala SERVQUAL de Parasuraman et al. (1988), composta por cinco dimensões: Tangibilidade, Empatia, Segurança, Confiabilidade e Responsabilidade. A escala SERVQUAL pretende medir a qualidade dos serviços com base nas expectativas dos clientes em contraste com a perceção que os mesmos têm em relação ao serviço que recebeu, e consequente satisfação ou insatisfação. A análise dos dados foi realizada a partir de uma estatística descritiva, a uma amostra probabilística de santomenses residentes em Portugal que recorrem aos serviços da Embaixada. A abordagem desta temática procura contribuir para a melhoria dos serviços prestados nesta Instituição mediante a perceção do nível de satisfação dos utentes, quer através da recolha de dados disponibilizados pela Embaixada quer com a aplicação do questionário aos utentes que a ela recorrem, para a apresentação de uma proposta de estratégias de marketing a serem utilizadas, com o objetivo de orientar para a melhoria e qualidade do serviço, e assim responder satisfatoriamente às necessidades e aos desejos dos seus clientes/utentes. Participaram no estudo uma amostra de 205 clientes/utentes da Embaixada, destes, 119 do sexo masculino e 86 do sexo feminino, com idade média de 50 anos. Os valores médios das expetativas dos inquiridos foram ligeiramente superiores às perceções dos serviços prestados, em todas as dimensões. Este estudo pretende trabalhar o contexto do marketing de serviço, em particular a satisfação e a qualidade dos serviços prestados, para perceber de que forma as organizações podem ter uma melhor orientação nos seus serviços no que diz respeito à satisfação dos desejos dos clientes num bom desempenho dos serviços prestados. Identificaram-se alguns GAPs principais que urgem serem trabalhados, nomeadamente o GAP2 (falhas quanto à “ausência de normas que regulam a prestação de serviços”) e o GAP3 (“não conformidade entre os serviços prestados e as normas existentes por deficiência dos meios ou do pessoal”) para os quais foram propostas ações de marketing para o futuro, com o objetivo de melhorar a qualidade dos serviços prestados pela Embaixada e respetiva satisfação dos clientes/utentes da Embaixada de STP em Portugal

Tautomerism of 4,4′-dihydroxy-1,1′-naphthaldazine studied by experimental and theoretical methods

BACKGROUND: The title compound belongs to the class of bis-azomethine pigments. On the basis of comparative studies on similar structures, insight into the complex excited state dynamics of such compounds has been gained. It has been shown, for example, that only compounds that possess hydroxyl groups are fluorescent, and that the possibility for cis-trans isomerisation and/or bending motions of the central bis-azomethine fragment allows for different non-radiative decay pathways. RESULTS: The compound, 4,4'-dihydroxy-1,1'-naphthaldazine (1) was synthesized and characterized by means of spectroscopic and quantum chemical methods. The tautomerism of 1 was studied in details by steady state UV-Vis spectroscopy and time resolved flash photolysis. The composite shape of the absorption bands was computationally resolved into individual subbands. Thus, the molar fraction of each component and the corresponding tautomeric constants were estimated from the temperature dependent spectra in ethanol. CONCLUSIONS: According to the spectroscopic data the prevalent tautomer is the diol form, which is in agreement with the theoretical (HF and DFT) predictions. The experimental data show, however, that all three tautomers coexist in solution even at room temperature. Relevant theoretical results were obtained after taking into account the solvent effect by the so-called supermolecule-PCM approach. The TD-DFT B3LYP/6-31 G** calculated excitation energies confirm the assignment of the individual bands obtained from the derivative spectroscopy

Cytotoxic and genotoxic effects of Br-containing oxaphosphole on Allium cepa L. root tip cells and mouse bone marrow cells

The continuous production and release of chemicals into the environment has led to the need to assess their genotoxicity. Numerous organophosphorus compounds with different structures have been synthesized in recent years, and several oxaphosphole derivatives are known to possess biological activity. Such chemical compounds may influence proliferating cells and cause disturbances of the genetic material. In this study, we examined the cytotoxicity and genotoxicity of 4-bromo-N,N-diethyl-5,5-dimethyl-2,5-dihydro-1,2-oxaphosphol-2-amine 2-oxide (Br-oxph). In A. cepa cells, Br-oxph (10-9 M, 10 -6 M and 10 -3 M) reduced the mitotic index 48 h after treatment with the two highest concentrations, with no significant effect at earlier intervals. Mitotic cells showed abnormalities 24 h and 48 h after treatment with the two lowest concentrations but there were no consistent changes in interphase cells. Bone marrow cells from mice treated with Br-oxph (2.82 x 10 -3 μg/kg) also showed a reduced mitotic index after 48 h and a greater percentage of cells with aberrations (principally chromatid and isochromatid breaks). These findings indicate the cytotoxicity and genotoxicity of Br-oxph in the two systems studied

Mesoscale simulations of confined Nafion thin films.

The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer

Low Al-content n-type AlxGa1-xN layers with a high-electron-mobility grown by hot-wall metalorganic chemical vapor deposition

In this work, we demonstrate the capability of the hot-wall metalorganic\ua0chemical vapor deposition\ua0to deliver high-quality\ua0n-AlxGa1−xN (x\ua0= 0\ua0–\ua00.12, [Si] = 1 71017\ua0cm−3)\ua0epitaxial layers\ua0on 4H-SiC(0001). All layers are crack-free, with a very small root mean square roughness (0.13\ua0–\ua00.25 nm), homogeneous distribution of Al over film thickness and a very low unintentional incorporation of oxygen at the detection limit of 5 71015\ua0cm−3\ua0and carbon of 2 71016\ua0cm−3. Edge type dislocations in the layers gradually increase with increasing Al content while\ua0screw dislocations\ua0only raise for\ua0x\ua0above 0.077. The room temperature\ua0electron mobility\ua0of the\ua0n-AlxGa1−xN remain in the range of 400\ua0–\ua0470 cm2/(V.s) for Al contents between 0.05 and 0.077 resulting in comparable or higher Baliga figure of merit with respect to GaN, and hence demonstrating their suitability for implementation as drift layers in power device applications. Further increase in Al content is found to result in significant deterioration of the electrical properties

A cost-effectiveness analysis of caspofungin vs. liposomal amphotericin B for treatment of suspected fungal infections in the UK

Objective: To evaluate the cost-effectiveness of caspofungin vs. liposomal amphotericin B in the treatment of suspected fungal infections in the UK.Methods: The cost-effectiveness of caspofungin vs. liposomal amphotericin B was evaluated using a decision-tree model. The decision tree was populated using both data and clinical definitions from published clinical studies. Model outcomes included success in terms of resolution of fever, baseline infection, absence of breakthrough infection, survival and quality adjusted life years (QALYs) saved. Discontinuation due to nephrotoxicity or other adverse events were included in the model. Efficacy and safety data were based on additional analyses of a randomised, double blind, multinational trial of caspofungin compared with liposomal amphotericin B. Information on life expectancy, quality of life, medical resource consumption and costs were obtained from peer-reviewed published data.Results: The caspofungin mean total treatment cost was £9762 (95% uncertainty interval 6955–12 577), which was £2033 (−2489; 6779) less than liposomal amphotericin B. Treatment with caspofungin resulted in 0.40 (−0.12; 0.94) additional QALYs saved in comparison with liposomal amphotericin B. Probabilistic sensitivity analysis found a 95% probability of the incremental cost per QALY saved being within the generally accepted threshold for cost-effectiveness (£30 000). Additional analyses with varying dose of caspofungin and liposomal amphotericin B confirmed these findings.Conclusion: Given the underlying assumptions, caspofungin is cost-effective compared with liposomal amphotericin B in the treatment of suspected fungal infections in the UK.<br/

On the anomalous optical conductivity dispersion of electrically conducting polymers: Ultra-wide spectral range ellipsometry combined with a Drude-Lorentz model

Electrically conducting polymers (ECPs) are becoming increasingly important in areas such as optoelectronics, biomedical devices, and energy systems. Still, their detailed charge transport properties produce an anomalous optical conductivity dispersion that is not yet fully understood in terms of physical model equations for the broad range optical response. Several modifications to the classical Drude model have been proposed to account for a strong non-Drude behavior from terahertz (THz) to infrared (IR) ranges, typically by implementing negative amplitude oscillator functions to the model dielectric function that effectively reduce the conductivity in those ranges. Here we present an alternative description that modifies the Drude model via addition of positive-amplitude Lorentz oscillator functions. We evaluate this so-called Drude-Lorentz (DL) model based on the first ultra-wide spectral range ellipsometry study of ECPs, spanning over four orders of magnitude: from 0.41 meV in the THz range to 5.90 eV in the ultraviolet range, using thin films of poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) as a model system. The model could accurately fit the experimental data in the whole ultrawide spectral range and provide the complex anisotropic optical conductivity of the material. Examining the resonance frequencies and widths of the Lorentz oscillators reveals that both spectrally narrow vibrational resonances and broader resonances due to localization processes contribute significantly to the deviation from the Drude optical conductivity dispersion. As verified by independent electrical measurements, the DL model accurately determines the electrical properties of the thin film, including DC conductivity, charge density, and (anisotropic) mobility. The ellipsometric method combined with the DL model may thereby become an effective and reliable tool in determining both optical and electrical properties of ECPs, indicating its future potential as a contact-free alternative to traditional electrical characterization. © The Royal Society of Chemistry 2019

On the anomalous optical conductivity dispersion of electrically conducting polymers: Ultra-wide spectral range ellipsometry combined with a Drude-Lorentz model

Electrically conducting polymers (ECPs) are becoming increasingly important in areas such as optoelectronics, biomedical devices, and energy systems. Still, their detailed charge transport properties produce an anomalous optical conductivity dispersion that is not yet fully understood in terms of physical model equations for the broad range optical response. Several modifications to the classical Drude model have been proposed to account for a strong non-Drude behavior from terahertz (THz) to infrared (IR) ranges, typically by implementing negative amplitude oscillator functions to the model dielectric function that effectively reduce the conductivity in those ranges. Here we present an alternative description that modifies the Drude model via addition of positive-amplitude Lorentz oscillator functions. We evaluate this so-called Drude-Lorentz (DL) model based on the first ultra-wide spectral range ellipsometry study of ECPs, spanning over four orders of magnitude: from 0.41 meV in the THz range to 5.90 eV in the ultraviolet range, using thin films of poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) as a model system. The model could accurately fit the experimental data in the whole ultrawide spectral range and provide the complex anisotropic optical conductivity of the material. Examining the resonance frequencies and widths of the Lorentz oscillators reveals that both spectrally narrow vibrational resonances and broader resonances due to localization processes contribute significantly to the deviation from the Drude optical conductivity dispersion. As verified by independent electrical measurements, the DL model accurately determines the electrical properties of the thin film, including DC conductivity, charge density, and (anisotropic) mobility. The ellipsometric method combined with the DL model may thereby become an effective and reliable tool in determining both optical and electrical properties of ECPs, indicating its future potential as a contact-free alternative to traditional electrical characterization. © The Royal Society of Chemistry 2019