A 3D-Printed Ceramics Innovative Firing Technique: A Numerical and Experimental Study.

Additive manufacturing (AM), also known as three-dimensional (3D) printing, allows the fabrication of complex parts, which are impossible or very expensive to produce using traditional processes. That is the case for dinnerware and artworks (stoneware, porcelain and clay-based products). After the piece is formed, the greenware is fired at high temperatures so that these pieces gain its mechanical strength and aesthetics. The conventional (gas or resistive heating elements) firing usually requires long heating cycles, presently requiring around 10 h to reach temperatures as high as 1200 °C. Searching for faster processes, 3D-printed stoneware were fired using microwave (MW) radiation. The pieces were fired within 10% of the conventional processing time. The temperature were controlled using a pyrometer and monitored using Process Temperature Control Rings (PTCRs). An error of 1.25% was calculated between the PTCR (1207 ± 15 °C) and the pyrometer (1200 °C). Microwave-fast-fired pieces show similar mechanical strength to the references and to the electrically fast-fired pieces (41, 46 and 34 (N/mm2), respectively), presenting aesthetic features closer to the reference. Total porosities of ~4%, ~5% and ~9% were determined for microwave, electrically fast-fired and reference samples. Numerical studies have shown to be essential to better understand and improve the firing process using microwave radiation. In summary, microwave heating can be employed as an alternative to stoneware conventional firing methods, not compromising the quality and features of the processed pieces, and with gains in the heating time.

Enhanced antibacterial activity of Rosehip extract-functionalized Mg(OH)2 nanoparticles: An in vitro and in vivo study.

The development of nanoparticles as antimicrobial agents against pathogenic bacteria has emerged as one of the leading global healthcare challenges. In this study, Mg(OH)2 NPs with controlled morphology and nanometric size, using two distinct counterions, chloride or nitrate, have been synthesized using Rosehip (RH) extract that has privileges beyond conventional chemical and physical methods. Various physicochemical techniques were used to characterize the RH-functionalized Mg-based NPs. They exhibited a spherical shape with a diameter of ~10 nm, low crystallinity compared to non-functionalized NPs, high polyphenol content, and negative zeta potential in three different media (H2O, TSB, and cell medium). The resulting RH-functionalized Mg-based NPs also exhibited an increased antibacterial activity against Gram-positive (S. Epidermis and S. aureus) and Gram-negative (E. Coli) bacteria compared to those prepared in pure water (0 % RH), an effect that was well evident with low NPs contents (250 µg/mL). A preliminary attempt to elucidate their mechanism of action revealed that RH-functionalized Mg-based NPs could disrupt cellular structures (bacterial cell wall and cytoplasmic membrane) and damage the bacterial cell, as confirmed by TEM imaging. Noteworthy is that Mg-based NPs exhibited higher toxicity to bacteria than to eukaryotic cells. More significantly, was their enhanced in vivo efficacy in a Galleria mellonella invertebrate animal model, when infected with S. aureus bacteria. Overall, our findings indicate that well-engineered Rosehip magnesium-based nanoparticles can be used as a green non-cytotoxic polyphenolic source in different antibacterial applications for the biomedical industry.

From Machining Chips to Raw Material for Powder Metallurgy-A Review.

Chips are obtained by subtractive processes such as machining workpieces and until recently considered as waste. However, in recent years they are shown to have great potential as sustainable raw materials for powder technologies. Powder production from metal chips, through the application of solid-state processes, seems to be an alternative to conventional atomization from liquid cooled with different fluids. However, chip material and processing have an essential role in the characteristics of powder particles, such as particle size, shape, size distribution and structure (4S's), which are essential parameters that must be considered having in mind the powder process and the metallurgy applications. Moreover, different approaches refereed in the application of this new "powder process" are highlighted. The goal is to show how the actual research has been transforming subtractive processes from a contributor of wastes to clean technologies.

Quality of Sleep among Portuguese Anaesthesiologists: A Cross-Sectional Study.

INTRODUCTION: Sleeping is essential to maintain proper relationships with others, keep alertness, and execute responsibilities, among many other functions. In the medical profession, there are several studies linking sleep deprivation with a decrease in responsiveness, cognition and attention. With this study we intended to characterize the sleep pattern of Portuguese anaesthesiologists and identify independent factors associated with sleep quality in this population. MATERIAL AND METHODS: An observational, cross-sectional study of senior and resident anesthesiologists working in Portugal was carried out through an online questionnaire. Individuals working exclusively in intensive care units, emergency departments or with previously diagnosed sleep disorders were excluded. Socio-demographic data, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and Perceived Stress Scale were applied. Statistical significance was assessed using the Mann-Whitney test and the chi-square test. A multivariable analysis was performed to examine the association between the Pittsburgh Sleep Quality Index and certain variables. RESULTS: Among 256 respondents, 46.1% reported "poor" quality of sleep (Pittsburgh Sleep Quality Index > 5). Within these individuals, 77.1% slept less than 7 hours per night (p < 0.001). Excessive daytime sleepiness (Epworth Sleepiness Scale > 10) was present in 41.0% of the sample, and the median Perceived Stress Scale score was 17.0. The independent factors associated with worse quality ofsleep were the number of working hours/week (OR 1.03, 95% CI 1,01 to 1,06), perceived stress (OR 1.18, 95% CI 1.11 to 1.26), taking sleep medication (OR 14.72, 95% CI 5.55 to 39.08), and sleep hours/night (OR 0.25, 95% CI 0.15 to 0.42). DISCUSSION: This fraction of Portuguese anaesthesiologists presented a poorer quality of sleep, with excessive daytime somnolence, perceived stress and higher sedative use compared to previously studied populations. CONCLUSION: Our study characterizes sleep patterns and identifies potential risk factors linked to sleep disturbances in a sample of Portuguese anaesthesiologists. Government and institutional policies can endorse sleep hygiene practices and habits, promoting healthier working environments.

Introdução: O sono é essencial para executar tarefas, manter o estado de alerta, executar tarefas, entre outras funções. Diversos estudos na área médica relacionam a privação de sono com a redução da capacidade de resposta, cognição e nível de atenção. Os objetivos deste estudo foram a caracterização do padrão de sono dos anestesiologistas Portugueses e identificação de fatores de risco independentes para pior qualidade de sono. Material e Métodos: Efetuámos um estudo observacional e transversal em anestesiologistas e internos de formação específica em Anestesiologia a trabalhar em Portugal. Foram excluídos profissionais que trabalham exclusivamente em unidades de cuidados intensivos, serviços de urgência ou com patologias do sono previamente diagnosticadas. Foram colhidos dados sócio-demográficos e aplicadas as escalas de Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) e Perceived Stress Scale (PSS). A significância estatística foi analisada recorrendo aos testes de Mann-Whitney e qui-quadrado. A associação entre o Pittsburgh Sleep Quality Index e demais variáveis foi testada através de uma regressão logística. Resultados: Dos 256 casos admitidos, 46,1% apresentaram "má" qualidade de sono (Pittsburgh Sleep Quality Index > 5). Nestes, 77,1% dormiram menos de 7 horas por noite (p < 0,001). A sonolência diurna excessiva (Epworth Sleepiness Scale > 10) surgiu em 41,0% da amostra e a mediana da Perceived Stress Scale foi 17,0. Os fatores de risco independentes para "má" qualidade de sono foram: número de horas de trabalho semanais (OR 1,03, IC 95% 1,01 a 1,06), stress percecionado (OR 1,18, IC 95% 1,11 a 1,26), toma de medicamentos para dormir (OR 14,72, IC 95% 5,55 a 39,08) e número de horas dormidas por noite (OR 0,25, IC 95% 0,15 a 0,42). Discussão: A nossa amostra de anestesiologistas Portugueses apresentou pior qualidade de sono, com sonolência diurna excessiva, stress percecionado e uso de sedativos superiores a outras populações previamente estudadas. Conclusão: O presente estudo caracteriza o padrão de sono e identifica potenciais factores de risco relacionados com distúrbios do sono, numa amostra de Anestesiologistas Portugueses. Políticas de saúde governamentais e institucionais poderão ser orientadas para a promoção da higiene do sono, levando a ambientes de trabalho mais saudáveis.

Effect of naloxone-3-glucuronide and N-methylnaloxone on the motility of the isolated rat colon after morphine.

The effect of the opioid antagonists naloxone-3-glucuronide and N-methylnaloxone on rat colon motility after morphine stimulation was measured. The rat model consisted of the isolated, vascularly perfused colon. The antagonists (10(-4) M, intraluminally) and morphine (10(-4) M, intra-arterially) were administered from 20 to 30 and from 10 to 50 min, respectively. Colon motility was determined by the luminal outflow. The antagonist concentrations in the luminal and venous outflow were measured by high-performance liquid chromatography. Naloxone-3-glucuronide and N-methylnaloxone reversed the morphine-induced reduction of the luminal outflow to baseline within 10 and 20 min, respectively. These antagonists were then excreted in the luminal outflow and could not be found in the venous samples. Naloxone, produced by hydrolysis or demethylation, was not detectable. In conclusion, highly polar naloxone derivatives peripherally antagonize the motility-lowering effect of morphine in the perfused isolated rat colon, are stable, and are not able to cross the colon-mucosal blood barrier.

Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography-mass spectrometry.

A method using gas chromatography-mass spectrometry (GC-MS) and solid-phase extraction (SPE) was developed for the determination of ajulemic acid (AJA), a non-psychoactive synthetic cannabinoid with interesting therapeutic potential, in human plasma. When using two calibration graphs, the assay linearity ranged from 10 to 750 ng/ml, and 750 to 3000 ng/ml AJA. The intra- and inter-day precision (R.S.D., %), assessed across the linear ranges of the assay, was between 1.5 and 7.0, and 3.6 and 7.9, respectively. The limit of quantitation (LOQ) was 10 ng/ml. The amount of AJA glucuronide was determined by calculating the difference in the AJA concentration before ("free AJA") and after enzymatic hydrolysis ("total AJA"). The present method was used within a clinical study on 21 patients suffering from neuropathic pain with hyperalgesia and allodynia. For example, plasma levels of 599.4+/-37.2 ng/ml (mean+/-R.S.D., n=9) AJA were obtained for samples taken 2 h after the administration of an oral dose of 20 mg AJA. The mean AJA glucuronide concentration at 2h was 63.8+/-127.9 ng/ml.