TIPS-triphenodioxazine versus TIPS-pentacene: Enhanced electron mobility for n-type organic field-effect transistors

A new soluble n-type material based on the 2,9-bis(triisopropylsilylethynyl)triphenodioxazine (TIPS-triphenodioxazine) has been designed as a quinonoid equivalent of TIPS-pentacene and synthesized using an innovative synthetic pathway. Both materials showed identical electronic affinities, intermolecular arrangements and thin film topographies. However, the TIPS-triphenodioxazine led to better performances than TIPS-pentacene in n-channel organic field-effect transistors (OFETs) evidencing the potentialities of this π-conjugated core in the field of organic electronics.     

Functional dependencies of C functions via weakest pre-conditions

We present functional dependencies, a convenient, formal, but high-level, specification format for a piece of procedural software (function). Functional dependencies specify the set of memory locations, which may be modified by the function, and for each modified location, the set of memory locations that influence its final value. Verifying that a function respects pre-defined functional dependencies can be tricky: the embedded world uses C and Ada, which have arrays and pointers. Existing systems we know of that manipulate functional dependencies, Caveat and SPARK, are restricted to pointer-free subsets of these languages. This article deals with the functional dependencies in a programming language with full aliasing. We show how to use a weakest pre-condition calculus to generate a verification condition for pre-existing functional dependencies requirements. This verification condition can then be checked using automated theorem provers or proof assistants. With our approach, it is possible to verify the specification as it was written beforehand. We assume little about the implementation of the verification condition generator itself. Our study takes place inside the C analysis framework Frama-C, where an experimental implementation of the technique described here has been implemented on top of the WP plug-in in the development version of the tool.     

至上主义的重现

我们的世界正在被多重的审美和意义重新构建着。全球一体化的浪潮不仅在横向空间中席卷了我们的生活,也将纵向的历史重新拉入这个时代:抽象主义与具象艺术对话,超现实主义与拉斐尔前派共存。风靡全球的IPHONE,IPAD等设计简洁的电子设备重新诠释了密斯著名的少即是多的名言,也给了反抗观念压迫的人们重拾信心的     

Catchment areas of medical practices and the role played by geographical distance in the patient’s choice of doctor

For a needs-planning system to be able to guarantee to provide the population with universal, locally available ambulatory medical care, it requires information concerning how patients choose their doctors, the size of the catchment areas of medical practices and the resulting distance-sensitivity of the population in relation to each medical speciality. In this contribution a model of opportunity’s preference for the health sector is developed. The key parameter of the distance sensitivity of the patients on the basis of real data is calibrated. Furthermore, this contribution empirically examines whether people in their choice of the established surgeons minimize the ways time (expense minimization) or if they are not aware of the nearest doctor, but the doctor of their confidence (act of preferential expression).     

Refractive index variations induced by femtosecond laser direct writing in the bulk of As2S3 glass at high repetition rate

This paper deals with the refractive index variation (Δn) induced by femtosecond laser irradiation in the bulk of As₂S₃ glass in a high repetition rate regime. Extensive measurements of spatially resolved Δn profiles of photowritten channels are reported for various values of the pulse energy. Nearly Gaussian profiles are obtained for energy slightly above the threshold whereas at higher energies the structure of Δn is more complex with a negative core surrounded by a positive ring. A thermal model is applied to reproduce the behaviour of the overall structure diameter.     

Exploring the statistical applicability of the Poincaré inequality: a test of normality

A new test of normality based on Poincaré inequality is proposed and analyzed. It rests on the characterization of the normal distribution given by Borovkov and Utev, i.e., a r.v. is normal if and only if its Poincaré constant is equal to its variance.     

Application of Thermodynamic Models for Better Understanding and Optimizing the Hall–Heroult Process

During the last decade, important improvements have been made in the application of thermodynamic models for studying the molten cryolite system used in the Hall?CHeroult process. This approach allows a better understanding and paves the way for furthering developments in bath chemistry and molten metal processing. In this article, thermodynamic modeling is used to explore the operating windows in the reduction of alumina in molten cryolite. The impact of a range of concentrations of AlF₃, CaF₂, and Al₂O₃ in conventional or ??lithium-free?? baths is also discussed. Subsequently, the model was also used to evaluate the impact of additions of lithium fluoride to the bath. Conditions allowing an operation at lower cell voltages and lower bath temperatures were identified. The modeling approach described in this article is considered as an important innovation to revisit fundamentals, to constantly re-examine paradigms, and to identify potential modifications?in bath chemistry for improving energy efficiency and productivity of modern prebaked Hall?CHeroult cells.     

Theoretical and experimental studies of (In,Ga)As/GaP quantum dots

(In,Ga)As/GaP(001) quantum dots (QDs) are grown by molecular beam epitaxy and studied both theoretically and experimentally. The electronic band structure is simulated using a combination of k·p and tight-binding models. These calculations predict an indirect to direct crossover with the In content and the size of the QDs. The optical properties are then studied in a low-In-content range through photoluminescence and time-resolved photoluminescence experiments. It suggests the proximity of two optical transitions of indirect and direct types.     

Inhibition of the catalytic oxidation of carbon/carbon composite materials by an aluminophosphate coating

The oxidation protection property of an aluminophosphate coating used to increase the lifetime of C/C composite materials has been investigated. This coating has already shown its ability to limit the thermal oxidation at high temperatures of C/C materials and we demonstrate in this paper its capacity to inhibit the catalytic oxidation. This catalytic oxidation, induced at low temperature by alkali and alkaline-earth elements (Na, K, Ca), is a crucial issue for aeronautical applications of C/C composite materials because of the presence of these catalytic elements in de-icing solutions used in airports. In addition, new information about the structure of the coating, prepared through the thermal treatment of a commercial aluminium phosphate solution, has been derived from XRD and solid-state NMR investigations.     

The effect of adsorbed species and exposure to sulfuric acid on the electrical conductance of individual single-wall carbon nanotube transistors

The electrical conductance of individual single-wall carbon nanotube (SWCNT) transistors was investigated before, during, and after soaking in concentrated sulfuric acid in air environment. The resulting doping effect has induced a shift of the Fermi level which was monitored by the electrical behavior and sought in Raman spectroscopy signature. For either metallic or semiconducting SWCNTs, the maximum conductance value was lowered during the contact with the acid; remained low for a short time after removing the acid; and recovered after long air exposure. This demonstrated the significant contribution of the physisorbed species in the measurements, specifically at the metal pad/SWCNT contact lines. The study also demonstrated that washing with sulfuric acid is an easy method for removing adsorbed species and reaching the intrinsic conductance of SWCNT-based devices.