Investigation of glow-discharge-induced morphology modifications on silicon wafers and chromium conversion coatings by AFM and rugosimetry

The effect of radiofrequency glow-discharge sputtering on the sample surface in terms of modifications in the surface morphology were investigated in this work by using atomic force microscopy (AFM) and rugosimetry measurements. The influence of GD operating parameters (e.g. rf power, discharge pressure and sputtering time) on surface roughening was investigated using two different types of samples: mirror-polished and homogeneous silicon wafers and chromate conversion coatings (CCCs). Surface morphology changes produced by GD sputtering into the sample surface were carefully investigated by AFM and rugosimetry, both at the original sample surface and at the bottom of GD craters using different GD experimental conditions, such as the sputtering time (from 1 s to 20 min), rf forward power (20–60 W for the Si wafer and 10–60 W for the CCC), and discharge pressure (400–1,000 Pa for the Si wafer and 500–1000 Pa for the CCC). In the present study, GD-induced morphology modifications were observed after rf-GD-OES analysis, both for the silicon wafers and the CCC. Additionally, the changes observed in surface roughness after GD sputtering were found to be sample-dependent, changing the proportion, shape and roughness of the micro-sized patterns and holes with the sample matrix and the GD conditions.     

A case study in formalizing projective geometry in Coq: Desargues theorem

Formalizing geometry theorems in a proof assistant like Coq is challenging. As emphasized in the literature, the non-degeneracy conditions lead to long technical proofs. In addition, when considering higher-dimensions, the amount of incidence relations (e.g. point–line, point–plane, line–plane) induce numerous technical lemmas. In this article, we investigate formalizing projective plane geometry as well as projective space geometry. We mainly focus on one of the fundamental properties of the projective space, namely Desargues property. We formally prove that it is independent of projective plane geometry axioms but can be derived from Pappus property in a two-dimensional setting. Regarding at least three-dimensional projective geometry, we present an original approach based on the notion of rank which allows to describe incidence and non-incidence relations such as equality, collinearity and coplanarity homogeneously. This approach allows to carry out proofs in a more systematic way and was successfully used to fairly easily formalize Desargues theorem in Coq. This illustrates the power and efficiency of our approach (using only ranks) to prove properties of the projective space.     

Quantitative full-colour transmitted light microscopy and dyes for concentration mapping and measurement of diffusion coefficients in microfluidic architectures

A simple and versatile methodology has been developed for the simultaneous measurement of multiple concentration profiles of colourants in transparent microfluidic systems, using a conventional transmitted light microscope, a digital colour (RGB) camera and numerical image processing combined with multicomponent analysis. Rigorous application of the Beer-Lambert law would require monochromatic probe conditions, but in spite of the broad spectral bandwidths of the three colour channels of the camera, a linear relation between the measured optical density and dye concentration is established under certain conditions. An optimised collection of dye solutions for the quantitative optical microscopic characterisation of microfluidic devices is proposed. Using the methodology for optical concentration measurement we then implement and validate a simplified and robust method for the microfluidic measurement of diffusion coefficients using an H-filter architecture. It consists of measuring the ratio of the concentrations of the two output channels of the H-filter. It enables facile determination of the diffusion coefficient, even for non-fluorescent molecules and nanoparticles, and is compatible with non-optical detection of the analyte.     

Transition-Metal-Free Synthesis of Oxindoles by Potassium tert-Butoxide-Promoted Intramolecular α-Arylation

Potassium tert-butoxide-mediated intramolecular α-arylations of fluoro- and chloro-substituted anilides provide oxindoles in DMF at 80 °C. In this manner, diversely substituted products have been obtained in moderate to high yields.     

Direct analysis of dried blood spots coupled with mass spectrometry: concepts and biomedical applications

Because of the emergence of dried blood spots (DBS) as an attractive alternative to conventional venous plasma sampling in many pharmaceutical companies and clinical laboratories, different analytical approaches have been developed to enable automated handling of DBS samples without any pretreatment. Associated with selective and sensitive MS–MS detection, these procedures give good results in the rapid identification and quantification of drugs (generally less than 3 min total run time), which is desirable because of the high throughput requirements of analytical laboratories. The objective of this review is to describe the analytical concepts of current direct DBS techniques and to present their advantages and disadvantages, with particular focus on automation capacity and commercial availability. Finally, an overview of the different biomedical applications in which these concepts could be of major interest will be presented.     

Structural and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 material prepared by a two-step synthesis via oxalate precursor

LiNi_1/3Co_1/3Mn_1/3O₂ (LNMCO) powders were formed by a two-step synthesis including preparation of an oxalate precursor by ??chimie douce?? followed by a solid-state reaction with lithium hydroxide. The product was characterized by TG-DTA, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy, electron spin resonance (ESR), and SQUID magnetometry. XRD data revealed well-crystallized layered LNMCO with ??-NaFeO₂-type structure (R-3?m space group). Morphology studied by SEM and TEM shows submicronic particles of 400?C800?nm with a tendency to agglomerate. The local structure investigated by vibrational spectroscopy (FTIR, Raman), ESR, and SQUID measurements confirms the well-crystallized lattice with a cation disorder of 2.6% Ni²⁺ ions in Li(3b) sites. Electrochemical tests were carried out in the potential range 2.5?C4.5?V vs. lithium metal on samples heated at 900?°C for 12?h. Initial discharge capacity is 154 mAh/g at C/5, while a capacity of 82 mAh/g is still delivered at 10 C by the two-step synthesized LiNi_1/3Co_1/3Mn_1/3O₂ as cathode material.     

A novel high-spin tridecanuclear Ni(II) cluster with an azido-bridged core exhibiting disk-like topology

A high-spin tridecanuclear Ni(II) cluster, [Ni(II)(13)(N(3))(18)(dpo)(4)(Hdpo)(2)(H(2)hpo)(4)(H(2)O)(MeOH)] [Ni(II)(13)(N(3))(18)(dpo)(4)(Hdpo)(2)(H(2)hpo)(4)(H(2)O)(2)] (1) (Hdpo = 1-(dimethylamino)propan-2-one oxime and H(2)hpo = 1-(hydroxyamino)propan-2-one oxime) with a purely azido-bridged core, is reported with dominant ferromagnetic coupling between Ni(II) ions. The latter molecule exhibits a unique planar core topology with the largest N(3)(-):Ni(II) ratio reported to date.     

Practical choice of ¹H-¹H decoupling schemes in through-bond ¹H-{X} HMQC experiments at ultra-fast MAS

Three (1)H-(1)H homonuclear dipolar decoupling schemes for (1)H indirect detection measurements at very fast MAS are compared. The sequences require the following conditions: (i) being operable at very fast MAS, (ii) a long T(2)(') value, (iii) a large scaling factor, (iv) a small number of adjustable parameters, (v) an acquisition window, (vi) a low rf-power requirement, and (vii) a z-rotation feature. To satisfy these conditions a modified sequence named TIlted Magic-Echo Sandwich with zero degree sandwich pulse (TIMES(0)) is introduced. The basic elements of TIMES(0) consist of one sampling window and two phase-ramped irradiations, which realize alternating positive and negative 360° rotations of (1)H magnetization around an effective field tilted with an angle θ from the B(0) axis. The TIMES(0) sequence benefits from very large chemical shift scaling factors at ultra-fast MAS that reach κ(cs)=0.90 for θ=25° at ν(r)=80kHz MAS and only four adjustable parameters, resulting in easy setup. Long κ(cs)T(2)(') values, where T(2)(') is a irreversible proton transverse relaxation time, greatly enhance the sensitivity in (1)H-{(13)C} through-bond J-HMQC (Heteronuclear Multiple-Quantum Coherence) measurements with (1)H-(1)H decoupling during magnetization transfer periods. Although similar sensitivity can be obtained with through-space D-HMQC sequences, in which (13)C-(1)H dipolar interactions are recoupled, J-HMQC experiments incorporating (1)H-(1)H decoupling benefit from lower t(1)-noise, more uniform excitation of both CH, CH(2) and CH(3) moieties, and easier identification of through-bond connectivities.     

Random pinning model with finite range correlations: Disorder relevant regime

The purpose of this paper is to show how one can extend some results on disorder relevance obtained for the random pinning model with i.i.d disorder to the model with finite range correlated disorder. In a previous work, the annealed critical curve of the latter model was computed, and equality of quenched and annealed critical points, as well as exponents, was proved under some conditions on the return exponent of the interarrival times. Here we complete this work by looking at the disorder relevant regime, where annealed and quenched critical points differ. All these results show that the Harris criterion, which was proved to be correct in the i.i.d case, remains valid in our setup. We strongly use Markov renewal constructions that were introduced in the solving of the annealed model.