Degradation characteristics of hydroxyapatite coatings on orthopedic TiAlV in simulated physiological media investigated by electrochemical impedance spectroscopy

This paper concentrates on the degradation characteristics of hydroxyapatite (HA) coatings on orthopaedic Ti-6Al-4V alloy while immersed in Ringer's salt solution, which were investigated by electrochemical impedance spectroscopy. Electrochemical impedance spectroscopy measurements were used to in situ characterize the electrochemical behavior of the passivated alloy covered with HA during aging in Ringer's solution. Comparison of the electrochemical data for the coated material with that for the uncoated metal substrate was also performed. The characteristic feature that describes the electrochemical behavior of the coated material is the coexistence of large areas of the coating itself with pores where the substrate is exposed to the aggressive media. The interpretation of results was thus performed in terms of a two-layer model of the film, in which the precipitation of hydrated oxide or phosphate compounds seals the pores left by the ceramic coating. The blocking effect due to salt precipitation inside the pores produces an enhancement of the resistance values, thus effectively diminishing the metal ion release in the system.Collaborative Research Programme (Acción Integrada No. HP1995-0092 and HP1996-0109) between Spain and Portugal

Patellar mechanics during simulated kneeling in the natural and implanted knee

AbstractKneeling is required during daily living for many patients after total knee replacement (TKR), yet many patients have reported that they cannot kneel due to pain, or avoid kneeling due to discomfort, which critically impacts quality of life and perceived success of the TKR procedure. The objective of this study was to evaluate the effect of component design on patellofemoral (PF) mechanics during a kneeling activity. A computational model to predict natural and implanted PF kinematics and bone strains after kneeling was developed and kinematics were validated with experimental cadaveric studies. PF joint kinematics and patellar bone strains were compared for implants with dome, medialized dome, and anatomic components. Due to the less conforming nature of the designs, change in sagittal plane tilt as a result of kneeling at 90° knee flexion was approximately twice as large for the medialized-dome and dome implants as the natural case or anatomic implant, which may result in additional stretching of the quadriceps. All implanted cases resulted in substantial increases in bone strains compared with the natural knee, but increased strains in different regions. The anatomic patella demonstrated increased strains inferiorly, while the dome and medialized dome showed increases centrally. An understanding of the effect of implant design on patellar mechanics during kneeling may ultimately provide guidance to component designs that reduces the likelihood of knee pain and patellar fracture during kneeling

Pitting corrosion of polycrystalline annealed copper in alkaline sodium perchlorate solutions containing benzotriazole

The pitting corrosion of copper in alkaline solutions in the presence of benzotriazole (BTA) was investigated. The presence of BTA shifts the breakdown (Eb) and the repassivating (Ep) potentials positively with respect to the blanks. However, the shift of Eb becomes smaller than that ofE b, particularly at pH9 and 11. Pitting corrosion involves the formation of crystallographic pits. The kinetics of the process fits a nucleation and growth mechanism involving instantaneous nucleation and 3D growth under charge transfer control. The spatial distribution of pits indicates that there is no marked influence of a pit on the nucleation and growth of other pits.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Synergistic Effects in the Inhibition of Copper Corrosion

Benzotriazole (BTA), thiourea (TU), and potassium ethylxanthate (KEX), behave as copper (Cu) corrosion inhibitors under certain conditions. These chemicals have been investigated to establish whether they provide synergistic effects. The Cu corrosion inhibition was followed through changes in electrochemical characteristics. Cu specimens were tested at 25°C in two aggressive media, 0.1 M NaCl and 1 M NaClO4, using the linear potential sweep technique at 0.001 V s–1 and by scanning electron microscopy of Cu specimens subjected to potentiodynamic and potentiostatic routines. A comparative behavior of the different substances for Cu was presented in the 6.6 ≤ pH ≤ 11 range. For KEX-BTA mixtures, synergistic inhibition effects were found in 0.1 M NaCl (7 ≤ pH ≤ 11). The apparent synergistic inhibition was explained tentatively by an increase in the compactness of the polymer-like passivating layer of KEX-Cu, which formed in the presence of BTA and Cl– ions.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Development of an affirming and customizable electronic survey of sexual and reproductive health experiences for transgender and gender nonbinary people

To address pervasive measurement biases in sexual and reproductive health (SRH) research, our interdisciplinary team created an affirming, customizable electronic survey to measure experiences with contraceptive use, pregnancy, and abortion for transgender and gender nonbinary people assigned female or intersex at birth and cisgender sexual minority women. Between May 2018 and April 2019, we developed a questionnaire with 328 items across 10 domains including gender identity; language used for sexual and reproductive anatomy and events; gender affirmation process history; sexual orientation and sexual activity; contraceptive use and preferences; pregnancy history and desires; abortion history and preferences; priorities for sexual and reproductive health care; family building experiences; and sociodemographic characteristics. Recognizing that the words people use for their sexual and reproductive anatomy can vary, we programmed the survey to allow participants to input the words they use to describe their bodies, and then used those customized words to replace traditional medical terms throughout the survey. This process-oriented paper aims to describe the rationale for and collaborative development of an affirming, customizable survey of the SRH needs and experiences of sexual and gender minorities, and to present summary demographic characteristics of 3,110 people who completed the survey. We also present data on usage of customizable words, and offer the full text of the survey, as well as code for programming the survey and cleaning the data, for others to use directly or as guidelines for how to measure SRH outcomes with greater sensitivity to gender diversity and a range of sexual orientations

Degradation of keratin substrates by keratinolytic fungi

Background: The hydrolysis of keratin wastes by microorganisms is considered a biotechnological alternative for recycling and valorization through keratinolytic microorganisms. Despite their resistant structure, keratin wastes can be efficiently degraded by various microorganisms through the secretion of keratinases,which are promising enzymes for several applications, including detergents, fertilizers, and leather and textile industry. In an attempt to isolate keratinolytic microorganisms that can reach commercial exploitation as keratinase producers, the current work assesses the dynamics of keratin biodegradation by several keratinolytic fungal strains isolated from soil. The activity of fungal strains to degrade keratin substrates was evaluated by SEM, FTRIR-ATR spectra and TGA analysis. Results: SEM observations offered relevant information on interactions between microorganism and structural elements of hair strands. FTIR spectra of the bands at 1035\u20131075 cm-1 assigned to sulfoxide bond appeared because of S\u2013S bond breaking, which demonstrated the initiation of keratin biodegradation. According to TGA, in the second zone of thermal denaturation, where keratin degradation occurs, the highest weight loss of 71.10% was obtained for sample incubated with Fusarium sp. 1A. Conclusions: Among the tested strains, Fusarium sp. 1A was the most active organism in the degradation process with the strongest denaturation of polypeptide chains. Because keratinolytic microorganisms and their enzymes keratinases represent a subject of scientific and economic interest because of their capability to hydrolyze keratin, Fusarium sp. 1A was selected for further studies

Theorising age and generation in development: A relational approach

This introduction outlines the analytical approach informing the articles presented in this special issue. The project of ‘generationing’ development involves re-thinking development as distinctly generational in its dynamics. For this, we adopt a relational approach to the study of young people in development, which overcomes the limitations inherent to common categorising approaches. Concepts of age and generation are employed to conceptualise young people as social actors and life phases such as childhood and youth in relational terms. Acknowledging the centrality of young people in social reproduction puts them at the heart of development studies and leads the articles comprising this special issue to explore how young people’s agency shapes and is shaped by the changing terms of social reproduction brought about by development

Prevalence and Factors Associated with Leishmania infantum Infection of Dogs from an Urban Area of Brazil as Identified by Molecular Methods

Visceral leishmaniasis (VL) is a disease caused by the parasite Leishmania infantum, and dogs are the most important domestic reservoirs of the agent. During recent decades, VL has expanded to large Brazilian urban centers. In the present work, we have demonstrated by using molecular techniques that the rate of canine infection as detected by serology has been considerably underestimated. Two groups of seronegative dogs (infected and non-infected according to molecular methods) were further evaluated from data obtained through interviews with owners of the animals. The factors associated with Leishmania infection in dogs were a family income of less than two minimum salaries, the knowledge of the owner regarding the vector, the dog spending most of its time in the backyard and the dog never having had a previous serological examination. Awareness regarding the factors associated with canine infection will improve health services and the understanding of the disease's expansion in urban areas