Additive Manufacturing of Fe-Mn-Si-Based Shape Memory Alloys: State of the Art, Challenges and Opportunities.

Additive manufacturing (AM) constitutes the new paradigm in materials processing and its use on metals and alloys opens new unforeseen possibilities, but is facing several challenges regarding the design of the microstructure, which is particularly awkward in the case of functional materials, like shape memory alloys (SMA), as they require a robust microstructure to withstand the constraints appearing during their shape change. In the present work, the attention is focused on the AM of the important Fe-Mn-Si-based SMA family, which is attracting a great technological interest in many industrial sectors. Initially, an overview on the design concepts of this SMA family is offered, with special emphasis to the problems arising during AM. Then, such concepts are considered in order to experimentally develop the AM production of the Fe-20Mn-6Si-9Cr-5Ni (wt%) SMA through laser powder bed fusion (LPBF). The complete methodology is approached, from the gas atomization of powders to the LPBF production and the final thermal treatments to functionalize the SMA. The microstructure is characterized by scanning and transmission electron microscopy after each step of the processing route. The reversibility of the ε martensitic transformation and its evolution on cycling are studied by internal friction and electron microscopy. An outstanding 14% of fully reversible thermal transformation of ε martensite is obtained. The present results show that, in spite of the still remaining challenges, AM by LPBF offers a good approach to produce this family of Fe-Mn-Si-based SMA, opening new opportunities for its applications.

Thermal Stability of Cu-Al-Ni Shape Memory Alloy Thin Films Obtained by Nanometer Multilayer Deposition.

Cu-Al-Ni is a high-temperature shape memory alloy (HTSMA) with exceptional thermomechanical properties, making it an ideal active material for engineering new technologies able to operate at temperatures up to 200 °C. Recent studies revealed that these alloys exhibit a robust superelastic behavior at the nanometer scale, making them excellent candidates for developing a new generation of micro-/nano-electromechanical systems (MEMS/NEMS). The very large-scale integration (VLSI) technologies used in microelectronics are based on thin films. In the present work, 1 µm thickness thin films of 84.1Cu-12.4 Al-3.5Ni (wt.%) were obtained by solid-state diffusion from a multilayer system deposited on SiNx (200 nm)/Si substrates by e-beam evaporation. With the aim of evaluating the thermal stability of such HTSMA thin films, heating experiments were performed in situ inside the transmission electron microscope to identify the temperature at which the material was decomposed by precipitation. Their microstructure, compositional analysis, and phase identification were characterized by scanning and transmission electron microscopy equipped with energy dispersive X-ray spectrometers. The nucleation and growth of two stable phases, Cu-Al-rich alpha phase and Ni-Al-rich intermetallic, were identified during in situ heating TEM experiments between 280 and 450 °C. These findings show that the used production method produces an HTSMA with high thermal stability and paves the road for developing high-temperature MEMS/NEMS using shape memory and superelastic technologies.

Temperature-Dependent Anisotropic Refractive Index in ß-Ga2O3: Application in Interferometric Thermometers.

An accurate knowledge of the optical properties of ß-Ga2O3 is key to developing the full potential of this oxide for photonics applications. In particular, the dependence of these properties on temperature is still being studied. Optical micro- and nanocavities are promising for a wide range of applications. They can be created within microwires and nanowires via distributed Bragg reflectors (DBR), i.e., periodic patterns of the refractive index in dielectric materials, acting as tunable mirrors. In this work, the effect of temperature on the anisotropic refractive index of ß-Ga2O3n(λ,T) was analyzed with ellipsometry in a bulk crystal, and temperature-dependent dispersion relations were obtained, with them being fitted to Sellmeier formalism in the visible range. Micro-photoluminescence (µ-PL) spectroscopy of microcavities that developed within Cr-doped ß-Ga2O3 nanowires shows the characteristic thermal shift of red-infrared Fabry-Perot optical resonances when excited with different laser powers. The origin of this shift is mainly related to the variation in the temperature of the refractive index. A comparison of these two experimental results was performed by finite-difference time-domain (FDTD) simulations, considering the exact morphology of the wires and the temperature-dependent, anisotropic refractive index. The shifts caused by temperature variations observed by µ-PL are similar, though slightly larger than those obtained with FDTD when implementing the n(λ,T) obtained with ellipsometry. The thermo-optic coefficient was calculated.

Shared decision making with schizophrenic patients: a randomized controlled clinical trial with booster sessions (DECIDE Study).

BACKGROUND: The treatment of schizophrenia requires a prolonged, multidimensional intervention that includes antipsychotic drugs. Treatment adherence is essential to effectively control the disorder. Shared decision-making (SDM) is a strategy, supported by numerous practical and ethical arguments, that seeks to involve patients in the therapeutic process to improve treatment adherence and satisfaction. The use of this model in mental health has been limited for many intrinsic and extrinsic reasons. The results of clinical trials conducted to date have largely been disappointing, potential due to study design-related limitations. AIM/QUESTION: To evaluate the efficacy, in terms of treatment adherence and improvement in clinical variables, such as severity of symptoms, days of hospitalization or insight, of a carefully timed SDM model initiated immediately prior to hospital discharge in patients with schizophrenia. METHODS: Single-blind, randomized clinical trial in an acute psychiatric care unit within the Andalusian Health Department to compare SDM (experimental group) to treatment as usual (TAU; control group) in a sample of patients hospitalized for an acute episode of schizophrenia or schizoaffective disorder. The study was performed between January 2014 and June 2017. The experimental group participated in SDM sessions prior to discharge with regular booster sessions over the one-year follow-up. The health care team responsible for SDM was predisposed to concordance (LatCon II scale) and received specific training in SDM. A hierarchical multiple linear regression analysis was performed to evaluate the factors independently associated with adherence, controlling for sociodemographic, clinical, and admission-related variables. Variables were assessed at admission, discharge and at 3, 6 and 12 months after discharge during the one year follow up. BARS, DAI, WAI-S, COMRADE and PANSS were used to evaluate adherence, attitude to treatment, therapeutic alliance, satisfaction and confidence with decision and clinical status, respectively. RESULTS: A total of 227 schizophrenic patients hospitalized with acute decompensation were evaluated; of these, 102 met all inclusion criteria and were included in the study. Most patients (95%) had prior experience with antipsychotics and most (82%) had experienced related side effects. Despite randomization, psychopathologic severity was greater in the experimental group, with a mean (SD) PANSS score of 104.08 (80) vs. 93.45 (20.30) (p < 0.05). The final regression model to explain adherence was significant (adjusted R2 = 0.384; F [df= 6] = 4.386; p < 0.001), with a direct, significant and independent association with SDM mediated by the number of booster sessions. DISCUSSION: Shared decision making with booster sessions appears to increase treatment adherence in patients with severe mental disorders. IMPLICATION ON PRACTICE: Ethical, practical, and clinical reasons support the use of strategies designed promote the use of long-term, shared decision-making in psychiatric patients, especially in schizophrenia spectrum disorder.

Designing for Shape Memory in Additive Manufacturing of Cu-Al-Ni Shape Memory Alloy Processed by Laser Powder Bed Fusion.

Shape memory alloys (SMAs) are functional materials that are being applied in practically all industries, from aerospace to biomedical sectors, and at present the scientific and technologic communities are looking to gain the advantages offered by the new processing technologies of additive manufacturing (AM). However, the use of AM to produce functional materials, like SMAs, constitutes a real challenge due to the particularly well controlled microstructure required to exhibit the functional property of shape memory. In the present work, the design of the complete AM processing route, from powder atomization to laser powder bed fusion for AM and hot isostatic pressing (HIP), is approached for Cu-Al-Ni SMAs. The microstructure of the different processing states is characterized in relationship with the processing parameters. The thermal martensitic transformation, responsible for the functional properties, is analyzed in a comparative way for each one of the different processed samples. The present results demonstrate that a final post-processing thermal treatment to control the microstructure is crucial to obtain the expected functional properties. Finally, it is demonstrated that using the designed processing route of laser powder bed fusion followed by a post-processing HIP and a final specific thermal treatment, a satisfactory shape memory behavior can be obtained in Cu-Al-Ni SMAs, paving the road for further applications.

Wide Dynamic Range Thermometer Based on Luminescent Optical Cavities in Ga2 O3 :Cr Nanowires.

Remote temperature sensing at the micro- and nanoscale is key in fields such as photonics, electronics, energy, or biomedicine, with optical properties being one of the most used transducing mechanisms for such sensors. Ga2 O3 presents very high chemical and thermal stability, as well as high radiation resistance, becoming of great interest to be used under extreme conditions, for example, electrical and/or optical high-power devices and harsh environments. In this work, a luminescent and interferometric thermometer is proposed based on Fabry-Perot (FP) optical microcavities built on Cr-doped Ga2 O3 nanowires. It combines the optical features of the Cr3+ -related luminescence, greatly sensitive to temperature, and spatial confinement of light, which results in strong FP resonances within the Cr3+ broad band. While the chromium-related R lines energy shifts are adequate for low-temperature sensing, FP resonances extend the sensing range to high temperatures with excellent sensitivity. This thermometry system achieves micron-range spatial resolution, temperature precision of around 1 K, and a wide operational range, demonstrating to work at least in the 150-550 K temperature range. Besides, the temperature-dependent anisotropic refractive index and thermo-optic coefficient of this oxide have been further characterized by comparison to experimental, analytical, and finite-difference time-domain simulation results.

Factors associated with the use of mechanical restraint in a mental health hospitalization unit: 8-year retrospective analysis.

WHAT IS ALREADY KNOWN ABOUT THE TOPIC?: Our present understanding of mechanical restraint is heterogenous, largely due to the important differences between countries/regions. In Spain, the use of this restrictive practice is not regulated, nor is its use protocolized. Previous studies that have investigated the impact of organizational factors and changes in these protocols are often short and not conducted within a framework designed to establish a long-term plan for reducing the use of mechanical restraint. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: We demonstrate that the implementation of administrative and protocol changes in our psychiatric unit significantly reduced the use of mechanical restraint, thus laying the foundations for a regulatory framework. Our analysis shows that the profile of patients who require mechanical restraint is highly variable, but that certain clinical and institutional aspects within the framework of a long-term plan for the reduction in mechanical restraint can be targeted with long-lasting positive effects. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Organizational changes focussed on training staff, promoting family support and requiring the registration and close monitoring of episodes empower the role of the nursing staff in the prevention, monitoring and regulation of mechanical restraint. ABSTRACT: Introduction Mechanical restraint is a controversial restrictive practice to manage agitation or violent behaviour. Numerous studies have evaluated the factors and organizational changes that influence on mechanical restraint, but only for short time periods. None of those studies have assessed the effects of measures applied within the framework of a long-term plan to reduce the use of mechanical restraint. Given the lack of specific legislation in Spain, more data are required for its proper regulation. Aim/Question To evaluate the risk factors associated and the impact of specific measures designed to minimize the application of mechanical restraint in an acute mental health unit over an 8-year period and previous observation of 5 years. Methods Cross-sectional study based on a retrospective analysis of mechanical restraint records. We compared admissions requiring ≥one episode of restraint versus admissions not requiring this coercive measure. Results Between 2007 and 2014, 412 admissions (12%) required mechanical restraint. The data show that the measures applied in the previous five years had significantly reduced the total hours of restraint per semester. The factors associated with admissions requiring mechanical restraint were involuntary, unscheduled and longer admissions. The best predictor of restraint was involuntary admission (OR = 6.37), followed by the diagnosis of personality disorder (OR = 5.01). Discussion Identification of the factors associated with mechanical restraint would allow for early detection strategies. Our results provide additional evidence on the usefulness of organizational changes to reduce coercive measures, even in a country without specific legislation. Implications for Practice Organizational changes, such as staff training and increased family support during admission of episodes of mechanical restraint, can reduce the use of this measure. These measures also give the nursing staff greater responsibility in terms of their role in registering and monitoring the restrictive practice, thus helping to prevent or minimize the use of mechanical restraint.

Near-UV optical cavities in Ga2O3 nanowires.

In this Letter, we report optical confinement in the near-ultraviolet (near-UV) range in Ga2O3 nanowires (NWs) by distributed Bragg reflector (DBR) nanopatterned cavities. High-contrast DBRs, which act as the end mirrors of the cavities of the desired length, are designed and fabricated by focused ion beam etching. The resonant modes of the cavities are analyzed by micro-photoluminescence measurements, analytical models, and simulations, which show very good agreement between each other. Experimental reflectivities up to 50% are obtained over the 350-410 nm region for the resonances in this wavelength range. Therefore, Ga2O3 NW optical cavities are shown as good candidates for single-material-based near-UV light emitters.

Risk factors for acute kidney injury in an enhanced recovery pathway for colorectal surgery.

PURPOSES: Enhanced recovery pathways (ERPs) have been disseminated worldwide to improve the perioperative patient outcomes while lowering direct healthcare costs. Recent evidence has revealed a potential association between ERPs for colorectal surgery and acute kidney injury (AKI). We, therefore, sought to identify the risk factors associated with postoperative AKI among patients in an ERP for colorectal surgery. METHODS: We analyzed the data resulting from a large multicenter, prospective cohort study of patients in an ERP for colorectal surgery. A multivariable analysis was performed to identify factors independently associated with postoperative AKI. The receiver operating characteristic (ROC) curves and contour representations were plotted for the diagnostic prediction analysis. RESULTS: Among those patients included in the analysis (n = 1652), the overall incidence of postoperative AKI was 7.7% (95% CI 6.5-9.1%). After adjustment, the independent risk factors for AKI included age > 60 (OR 1.03, 95% CI 1.01-1.05), male gender (OR 2.33, 95% CI 1.36-4.02), ASA III-IV (OR 2.43, 95% CI 1.39-4.26), CKD (OR 2.45, 95% CI 1.42-4.23), open surgical approach (OR 2.62, 95% CI 1.63-4.21) and serum albumin < 3.5 g/dL (OR 1.68, 95% CI 1.02-2.79). An ROC analysis revealed that the composite of albumin, creatinine and age was a strong predictor of postoperative AKI [area under the curve (AUC) 0.756; 95% CI 0.705-0.808]. CONCLUSION: Postoperative AKI is common in the setting of ERPs for colorectal surgery and it is associated with a poor clinical outcome. Of those characteristics associated with postoperative AKI, one modifiable factor is a low preoperative albumin level. Screening for malnourished patients or optimizing the nutritional status may be a useful preoperative intervention to prevent postoperative AKI and associated complications.

Patología dual en personas sin hogar en el Área de Salud de Avilés / Dual pathology in homeless people in the Avilés Health Area

El objetivo principal del presente estudio es estimar la prevalencia de trastornos mentales graves y de uso de sustancias en personas en la situación de estar sin hogar. El trabajo se realizó a partir de los datos obtenidos de una muestra representativa de personas sin hogar en Avilés (Asturias) (n=100) utilizando la Entrevista Neuropsiquiátrica Internacional (M.I.N.I.). Los resultados de nuestro estudio ponen de manifiesto una estrecha relación entre el uso de sustancias y el sinhogarismo. Más de la mitad de las personas sin hogar tiene trastornos relacionados con el uso de sustancias en comparación con el uso problemático de sustancias en la población general. Se discute la atención psicosocial y la organización de una red de apoyo a las personas sin hogar. (AU)

The main objective of the present study is to estimate the prevalence of severe mental disorders and substance use in the homeless situation. The work was carried out from the data obtained from a representative sample of homeless people in Avilés (Asturias) (n = 100) using the International Neuropsychiatric Interview (M.I.N.I.). The results of our study reveal a close relationship between substance use and homelessness. More than half of the homeless have substance use disorders compared to problem substance use in the general population. Psychosocial care and the organization of a support network for the homeless are discussed. (AU)

Dual pathology in homeless people in the Avilés Health Area / Patología dual en personas sin hogar en el Área de Salud de Avilés

The main objective of the present study is to estimate the prevalence of severe mental disorders and substance use in the homeless situation. The work was carried out from the data obtained from a representative sample of homeless people in Avilés (Asturias) (n = 100) using the International Neuropsychiatric Interview (M.I.N.I.). The results of our study reveal a close relationship between substance use and homelessness. More than half of the homeless have substance use disorders compared to problem substance use in the general population. Psychosocial care and the organization of a support network for the homeless are discussed. (AU)

El objetivo principal del presente estudio es estimar la prevalencia de trastornos mentales graves y de uso de sustancias en personas en la situación de estar sin hogar. El trabajo se realizó a partir de los datos obtenidos de una muestra representativa de personas sin hogar en Avilés (Asturias) (n=100) utilizando la Entrevista Neuropsiquiátrica Internacional (M.I.N.I.). Los resultados de nuestro estudio ponen de manifiesto una estrecha relación entre el uso de sustancias y el sinhogarismo. Más de la mitad de las personas sin hogar tiene trastornos relacionados con el uso de sustancias en comparación con el uso problemático de sustancias en la población general. Se discute la atención psicosocial y la organización de una red de apoyo a las personas sin hogar. (AU)

Size effect and scaling power-law for superelasticity in shape-memory alloys at the nanoscale.

Shape-memory alloys capable of a superelastic stress-induced phase transformation and a high displacement actuation have promise for applications in micro-electromechanical systems for wearable healthcare and flexible electronic technologies. However, some of the fundamental aspects of their nanoscale behaviour remain unclear, including the question of whether the critical stress for the stress-induced martensitic transformation exhibits a size effect similar to that observed in confined plasticity. Here we provide evidence of a strong size effect on the critical stress that induces such a transformation with a threefold increase in the trigger stress in pillars milled on [001] L21 single crystals from a Cu-Al-Ni shape-memory alloy from 2 µm to 260 nm in diameter. A power-law size dependence of n = -2 is observed for the nanoscale superelasticity. Our observation is supported by the atomic lattice shearing and an elastic model for homogeneous martensite nucleation.