Influence of Electrodeposition Parameters on Morphology and Polymer Inclusion into Polymer/Zn Composite Coatings

In this study different type of composite coatings was obtained by electrodeposition using zinc as matrix and polymeric particles as disperse phase in zinc sulphate electrolyte. The effects of some electrodeposition parameters on the thickness and morphology of obtained composite coatings were analysed by optical microscopy, Scanning Electron Microscopy (SEM) and Energy-Dispersive X-Ray Spectroscopy (EDX) methods. Polymeric particles inclusion into zinc matrix was correlated with imposed electrodeposition parameters. It was observed that the thickness of the coatings is influenced by electrodeposition parameters. From the morphology of the coatings, it could be concluded that pure zinc has a regular surface with hexagonal crystals, while the composite coatings have fine surface structure. Also, the electrodeposition parameters influence the inclusion of the dispersed phase into metallic matrix that will influence further the different properties of the composite materials.

Direction Curves Associated with Darboux Vectors Fields and Their Characterizations

In this paper, we consider the Darboux frame of a curve α lying on an arbitrary regular surface and we use its unit osculator Darboux vector D ¯ o , unit rectifying Darboux vector D ¯ r , and unit normal Darboux vector D ¯ n to define some direction curves such as D ¯ o -direction curve, D ¯ r -direction curve, and D ¯ n -direction curve, respectively. We prove some relationships between α and these associated curves. Especially, the necessary and sufficient conditions for each direction curve to be a general helix, a spherical curve, and a curve with constant torsion are found. In addition to this, we have seen the cases where the Darboux invariants δ o , δ r , and δ n are, respectively, zero. Finally, we enrich our study by giving some examples.

Surfaces with canonical map of maximum degree

We use the Borisov-Keum equations of a fake projective plane and the Borisov-Yeung equations of the Cartwright-Steger surface to show the existence of a regular surface with canonical map of degree 36 and of an irregular surface with canonical map of degree 27. As a by-product, we get equations (over a finite field) for the Z / 3 \mathbb {Z}/3 -invariant fibres of the Albanese fibration of the Cartwright-Steger surface and show that they are smooth.

Some Special Ruled Surfaces Generated by a Direction Curve according to the Darboux Frame and their Characterizations

In this work, we consider the Darboux frame T , V , U of a curve lying on an arbitrary regular surface and we construct ruled surfaces having a base curve which is a V -direction curve. Subsequently, a detailed study of these surfaces is made in the case where the directing vector of their generatrices is a vector of the Darboux frame, a Darboux vector field. Finally, we give some examples for special curves such as the asymptotic line, geodesic curve, and principal line, with illustrations of the different cases studied.

Dynamics and Stability of Non-Smooth Dynamical Systems with Two Switches

One of the most common hypotheses on the theory of non-smooth dynamical systems is a regular surface as switching manifold, at which case there is at least well-defined and established Filippov dynamics. However, systems with singular switching manifolds still lack such well-established dynamics, although present in many relevant models of phenomena where multiple switches or multiple abrupt changes occur. At this work, we leverage a methodology that, through blow-ups and singular perturbation, allows the extension of Filippov dynamics to the singular case. Specifically, tridimensional systems whose switching manifold consists of an algebraic manifold with transversal self-intersection are considered. This configuration, known as double discontinuity, represents systems with two switches and whose singular part consists of a straight line, where ordinary Filippov dynamics is not directly applicable. For the general, non-linear case, beyond defining the so-called fundamental dynamics over the singular part, general theorems on its qualitative behavior are provided. For the affine case, however, theorems fully describing the fundamental dynamics are obtained. Finally, this fine-grained control over the dynamics is leveraged to derive Peixoto-like theorems characterizing semi-local structural stability.

Simultaneous Developability of Partner Ruled Surfaces according to Darboux Frame in E 3

In this paper, we introduce original definitions of Partner ruled surfaces according to the Darboux frame of a curve lying on an arbitrary regular surface in E 3 . It concerns T g Partner ruled surfaces, T n Partner ruled surfaces, and g n Partner ruled surfaces. We aim to study the simultaneous developability conditions of each couple of two Partner ruled surfaces. Finally, we give an illustrative example for our study.

Giant uterine leiomyoma delivered through the cervix: About three cases in Ouagadougou

INTRODUCTION: Giant uterine leimyofibromas delivered through the uterine cervix are rare. MATERIALS AND METHODS: We report 3 observations in order to describe our diagnostic and therapeutic approach. RESULTS: Three patients aged 40, 49 and 41 years were seen for intense pelvic pain associated with metrorrhagia and a feeling of pelvic heaviness. The average delay of consultation was three years. They were all multiparous. The gynecological examination revealed a firm tissue mass with a smooth and regular surface of eight cm on average, occupying the vaginal cavity while respecting the vaginal walls. Speculum examination was not possible because of the size of the mass which was flush with the lower third of the vagina. Magnetic resonance imaging concluded to a myoma delivered through the cervix in all patients. A total hysterectomy was performed. Histology of the total hysterectomy specimen concluded a uterine leiomyoma of the uterus. CONCLUSION: These giant uterine leiomyomas are rare. Magnetic resonance imaging describes them well. The treatment is most often a total hysterectomy in women who do not wish to have pregnant.

Smarandache Ruled Surfaces according to Darboux Frame in E 3

This paper presents a new approach of constructing special ruled surfaces and aims to study their developability and minimalist conditions. Our concept opens opportunities for application in engineering, surface modeling, and architectural design. The principle of our study is to introduce the original definitions of Smarandache ruled surfaces according to Darboux frame of a curve lying on an arbitrary regular surface in E 3 . It concerns T g -Smarandache ruled surface, T n -smarandache ruled surface, and g n -Smarandache ruled surface. New theorems giving necessary and sufficient conditions for those surfaces to be developable and minimal are investigated. Finally, an example with illustrations is presented.

SARS-CoV-2 Detection Rates from Surface Samples Do Not Implicate Public Surfaces as Relevant Sources for Transmission

Contaminated surfaces have been discussed as a possible source of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Under experimental conditions, SARS-CoV-2 can remain infectious on surfaces for several days. However, the frequency of SARS-CoV-2 detection on surfaces in healthcare settings and the public is currently not known. A systematic literature review was performed. On surfaces around COVID-19 cases in healthcare settings (42 studies), the SARS-CoV-2 RNA detection rates mostly were between 0% and 27% (Ct values mostly > 30). Detection of infectious SARS-CoV-2 was only successful in one of seven studies in 9.2% of 76 samples. Most of the positive samples were obtained next to a patient with frequent sputum spitting during sampling. Eight studies were found with data from public surfaces and RNA detection rates between 0% and 22.1% (Ct values mostly > 30). Detection of infectious virus was not attempted. Similar results were found in samples from surfaces around confirmed COVID-19 cases in non-healthcare settings (7 studies) and from personal protective equipment (10 studies). Therefore, it seems plausible to assume that inanimate surfaces are not a relevant source for transmission of SARS-CoV-2. In public settings, the associated risks of regular surface disinfection probably outweigh the expectable health benefits.

Sweeping surface of center curve on surface in Euclidean 3-space E³

For the curve on the regular surface, there is moving frame with this thatis named Darboux frame. Sweeping surfaces through the curve associated with Darboux frame are introduced and their geometrical properties are investigated. Moreover, we obtain the necessary and sufficient conditions of this kind of surfaces to be developable ruled surfaces. Finally, an example to illustrate the application of the results is introduced.