Effects of incidence angles of ions on the mass resolution of an energy compensated 3D atom probe

We have used a first-order reflectron lens in an optical tomographic atom probe in order to improve the mass resolution. Calculations have been performed to determine the effect of second-order errors in ion energy and incidence angle on the performance of the lens. By applying a correction procedure based on the results of these calculations, we have been able to improve experimental mass resolution by 30%.     

The role of hindered Lewis bases on the catalyst performance of TiCl3 for propylene polymerization

Summary The effect of AlEt₃ modified by tributylamine (TBA), 1,4-diazabicyclo [2.2.2]octan (DO), 2,2,6,6-tetramethylpiperidine (TMPip), 2,6-dibutyl-4-methylphenol (BHT) and 2-tert-butyl-4-metoxyphenol (TBMP) on the propylene polymerization was studied using a catalyst based on TiCl₃ modified with di-n-butyl ether as internal base. The influence of these hindered Lewis bases on the isotacticity, catalyst activity, molecular weight ( n) and molecular weight distribution (MWD) was investigated. It was verified that the Lewis bases modified the percentage of mm triad whereas no significant effect on I.I. was found.     

Chilean medicine immediately after the 1891 revolution

The conflict between the Chilean President Balmaceda and the parliament lead him to rule the country despotically during 8 months, until his suicide in 1891. During this lapse he persecuted and imprisoned his opponents, including several Medical School professors. Doctor David Benavente, professor of Anatomy and Balmaceda's opponent, wrote a chronicle at the Revista Médica de Chile (1897; 20:46) referring to the changes that occurred at the Medical School: "Flogged by dictatorship's winds, it barely gave sings of life during the eight months that Balmaceda dominated the country". Political passion almost annihilated for ever the first scientific teaching center of the University of Chile, posed a project at the Public Instruction Council "to create in all high schools a special class about the general principles of the Constitution". Once democratic normality was re-established, the development of Chilean Medicine was greatly impelled, sending young physicians to specialize at qualified european centers.     

Transcervical chorionic villus sampling beyond 12 weeks of gestation

While patients with esophageal cancer are operated, a large quantity of non-functional extracelluler fluid (ECF) are appeared. Mediastinum, intestines, visceral vessels, wound of thoracotomy and laparotomy, etc, become so called "third space", then much water, Na are shifted and restored there. Moreover, plenty of water are evaporated from operated fields and lymph issues are active. A long time ago, intraoperative fluid infusion was little, but recently more fluid (Hartmann solution) are infused (8 approximately 10/ml/kg/hr). Intraoperative blood transfusion is often done because blood tends to lose. But it sometimes had serious side effects, example for GVHD (graft-versus-host disease), infections. In order to prevent from thease, autotransfusion and irradiation to transfused blood are recommended.     

The impact of shift and night work on health

Shift work, in particular night work, can have a negative impact on health and well-being of workers as it can cause: (a) disturbances of the normal circadian rhythms of the psychophysiological functions, beginning with the sleep/wake cycle; (b) interferences with work performance and efficiency over the 24 hour span, with consequent errors and accidents; (c) difficulties in maintaining the usual relationships both at family and social level, with consequent negative influences on marital relations, care of children and social contacts; (d) deterioration of health that can be manifested in disturbances of sleeping and eating habits and, in the long run, in more severe disorders that deal prevalently with the gastrointestinal (colitis, gastroduodenitis and peptic ulcer), neuro-psychic (chronic fatigue, anxiety, depression) and, probably, cardiovascular (hypertension, ischemic heart diseases) functions. Besides, shift and night work may have more specific adverse effects on women's health both in relation to their particular hormonal and reproductive function, and their family roles. It has been estimated that about 20% of all workers have to leave shift work in a very short time because of serious disturbances; those remaining in shift work show different levels of (mal)adaptation and (in)tolerance, that can become more or less manifest in different times, and with different intensity. In fact, the effects of such stress condition can vary widely among the shift workers in relation to many 'intervening variables' concerning both individual factors (e.g. age, personality traits, physiological characteristics), as well as working situations (e.g. work loads, shift schedules) and social conditions (e.g. number and age of children, housing, commuting).     

Boosting Room‐Temperature Magneto‐Ionics in a Non‐Magnetic Oxide Semiconductor

Voltage control of magnetism through electric field‐induced oxygen motion (magneto‐ionics) could represent a significant breakthrough in the pursuit for new strategies to enhance energy efficiency in magnetically actuated devices. Boosting the induced changes in magnetization, magneto‐ionic rates and cyclability continue to be key challenges to turn magneto‐ionics into real applications. Here, it is demonstrated that room‐temperature magneto‐ionic effects in electrolyte‐gated paramagnetic Co₃O₄ films can be largely increased both in terms of generated magnetization (6 times larger) and speed (35 times faster) if the electric field is applied using an electrochemical capacitor configuration (utilizing an underlying conducting buffer layer) instead of placing the electric contacts at the side of the semiconductor (electric‐double‐layer transistor‐like configuration). This is due to the greater uniformity and strength of the electric field in the capacitor design. These results are appealing to widen the use of ion migration in technological applications such as neuromorphic computing or iontronics in general.     

The Use of Active Methodologies for Teaching–Learning Systems in Telecommunications

This article discusses the adoption of the Problem Based Learning (PBL) and Project Based Learning (P2BL) approaches in the teaching/learning process of telecommunications. A computational environment was defined to combine these two approaches which focused on the teaching of courses that cover topics related to telecommunications systems. Newly graduated professionals face difficulties when entering the job market, as they have to deal with situations that are not experienced in the academic world. There is still a tendency to rely on traditional approaches for the teaching of telecommunications systems that have proved to be inefficient, as they are only concerned with content and not the applications that the student will require in the job market. The aim of this research is to investigate whether the adoption of PBL and P2BL in a computational environment can enhance student learning more effectively than the traditional teaching approach. This involved conducting an experiment in 7 undergraduate classes to compare the performance of the students that adopted PBL and P2BL with that of the students who were taught with the traditional approach. Data were collected on the grades obtained by the students in the courses and these were statistically analyzed. The results show that the adoption of PBL and P2BL led to the students achieving a 32% increase in performance. However, it was noted that the infrastructure of the institutions directly influences the way the approaches are adopted and, hence affects, the results.

     

Binary and Ternary Mixtures of Biopolymers and Water: Viscosity,Refractive Index,and Density

Biopolymers have been the focus of intense research because of their wide applicability. The thermophysical properties of solutions containing biopolymers have fundamental importance for engineering calculations, as well as for thermal load calculations, energy expenditure, and development of new products. In this work, the thermophysical properties of binary and ternary solutions of carboxymethylcellulose and/or high methoxylation pectin and water at different temperatures have been investigated taking into consideration different biopolymer concentrations. The experimental data related to the thermophysical properties were correlated to obtain empirical models that can describe the temperature–concentration combined effect on the density, refractive index, and dynamic viscosity. From data obtained from the experiments, the density, refractive index, and dynamic viscosity increase with increasing biopolymer concentration and decrease with increasing temperature. The polynomial models showed a good fit to the experimental data and high correlation coefficients (\(R^{2}\ge \) 0.98) for each studied system.     

Precompensated Second Order Repetitive Control of an Active Filter Under Varying Network Frequency

Network frequency variations cause a dramatic performance decay in repetitive controller‐based shunt active power filters. This problem may be solved by adapting the sampling period in order to keep the ratio between the network period and the sampling period at a constant value. However, these changes may yield closed‐loop instability. The introduction of a precompensator that forces the plant to remain invariant despite sampling rate changes allows the use of standard LTI methods in control design and stability analysis as well. Moreover, in order to improve robustness in the face of network frequency estimation uncertainty and sampling time quantization, the regular repetitive controller is replaced by a high order one. Experimental results show the validity of the proposal.