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Evaporation control is a critical facility resource during solidification experiments that limits processing time and must be tracked to ensure facility health. A thermodynamic analysis was performed on a ternary FeCrNi sample processed onboard the International Space Station (ISS) using ESA Electromagnetic Levitation (EML) facility in a microgravity environment. A non-ideal solution-based mathematical model was applied for the overall sample mass loss prediction during this study. The overall sample mass loss prediction is consistent with the post-flight mass loss measurements. The species-specific findings from this study were validated using post-mission SEM-EDX surface evaluations by three different facilities. The bulk composition prediction was validated using SEM-EDX and wet chemical analysis. The non-ideal solution model was then applied to predict the composition of the dust generated during EML testing. The thicknesses of the deposited layer on the EML coil at various locations were also calculated using the geometry of the facility and results were validated with near-real-time dust layer predictions from toxicity tracking software developed by the German Space Center (DLR) Microgravity User Support Center (MUSC)., (© 2024. The Author(s).)

Space levitation processing allows researchers to conduct benchmark tests in an effort to understand the physical phenomena involved in rapid solidification processing, including alloy thermodynamics, nucleation and growth, heat and mass transfer, solid/liquid interface dynamics, macro- and microstructural evolution, and defect formation. Supported by ground-based investigations, a major thrust is to develop and refine robust computational tools based on theoretical and applied approaches. This work is accomplished in conjunction with experiments designed for precise model validation with application to a broad range of industrial processes., (© 2023. Springer Nature Limited.)

A new method for quantifying facility performance has been discussed in this study that encompasses uncertainties associated with thermophysical property measurement. Four key thermophysical properties: density, volumetric thermal expansion coefficient, surface tension, and viscosity of liquid Au have been measured in microgravity environment using two different levitation facilities. Levitation experiments were conducted using the Electrostatic Levitation Furnace (ELF) onboard the ISS in Argon and air, and the TEMPUS Electromagnetic Levitation (EML) facility on a Novespace Zero-G aircraft parabolic flight in Argon. The traditional Maximum Amplitude method was augmented through the use of Frequency Crossover method to identify the natural frequency for oscillations induced on a molten sample during Faraday forcing in ESL. The EML tests were conducted using a pulse excitation method where two techniques, one imaging and one non-imaging, were used to study surface oscillations. The results from both facilities are in excellent agreement with the published literature values. A detailed study of the accuracy and precision of the measured values has also been presented in this work to evaluate facility performance., (© 2023. The Author(s).)

Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial step in the industrial solidification of metallic alloy melts and are greatly influenced by the thermophysical properties of the melt. Knowledge of the thermophysical properties of liquid metallic alloys is necessary in order to gain a tight control over the solidification pathway, and over the obtained material structure of the solid. Measurements of thermophysical properties on ground are often difficult, or even impossible, since liquids are strongly influenced by earth's gravity. Another problem is the reactivity of melts with container materials, especially at high temperature. Finally, deep undercooling, necessary to understand nucleus formation and equilibrium as well as non-equilibrium solidification, can only be achieved in a containerless environment. Containerless experiments in microgravity allow precise benchmark measurements of thermophysical properties. The electromagnetic levitator ISS-EML on the International Space Station (ISS) offers perfect conditions for such experiments. This way, data for process simulations is obtained, and a deeper understanding of nucleation, crystal growth, microstructural evolution, and other details of the transformation from liquid to solid can be gained. Here, we address the scientific questions in detail, show highlights of recent achievements, and give an outlook on future work., (© 2023. The Author(s).)

CDC is the nation's premier health promotion, prevention, and preparedness agency. As such, CDC is an important source of public health and clinical guidelines. If CDC guidelines are to be trusted by partners and the public, they must be clear, valid, and reliable. Methods and processes used in CDC guideline development should follow universally accepted standards. This report describes the standards required by CDC for the development of evidence-based guidelines. These standards cover topics such as guideline scoping, soliciting external input, summarizing evidence, and crafting recommendations. Following these standards can help minimize bias and enhance the quality and consistency of CDC guidelines., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Introduction: The current COVID-19 disease pandemic has delayed nonurgent orthopaedic procedures to adequately care for those affected by the severe acute respiratory syndrome coronavirus 2, resulting in a backlog in orthopaedic surgical care. As the capacity for orthopaedic surgeries expands or contracts, allocation of limited resources in a manner that adequately reflects medical necessity and urgency is paramount. An orthopaedic surgery-specific prioritization schema with proven reliability is lacking. The primary aim of this study was to assess the reliability of a newly developed prioritization list used for the phased reinstatement of orthopaedic surgical procedures during the COVID-19 pandemic and afterward. The secondary aim was to report its implementation., Methods: A consensus-based, orthopaedic surgery-specific, tiered prioritization list reflecting various levels of urgency was created by a committee of orthopaedic surgeons covering all subspecialties and representing academic, multispecialty, and private community practices. Reliability was tested for 63 randomized cases representing all orthopaedic subspecialties. Four raters evaluated the cases independently at two separate time points, at least one week apart. Fleiss kappa was used to assess intrarater and interrater agreement. Implementation were assessed by surveying both surgeons and the surgery scheduling administrative personnel at each surgical facility within a large health system for any adoption issues., Results: Case distributions within tiers 1, 2, 3, and 4 were 35%, 14%, 27%, and 24%, respectively. Interrater agreement ranged from 0.63 (95% confidence interval [CI] 0.57 to 0.69) to 0.72 (95% CI 0.66 to 0.78) for the ratings. Intrarater reliability ranged from 0.62 to 1.0. The highest levels of agreement were in tiers 1, 4, and the subspecialties oncology and foot/ankle. The time from development to full scale adoption and implementation by all orthopaedic surgeons was rapid., Discussion: This tiered prioritization list for orthopaedic procedures is both adoptable and reliable during the phased reinstatement of procedures during the COVID-19 pandemic and afterward. Further refinements may enhance utility., Levels of Evidence: Reliability study: Level I (Evid Based Spine Care J 2014 October;5(2):166. doi: 10.1055/s-0034-1394106)., (Copyright © 2020 by the American Academy of Orthopaedic Surgeons.)

Oscillating droplet experiments are conducted using the Electromagnetic Levitation (EML) facility under microgravity conditions. The droplet of molten metal is internally stirred concurrently with the pulse excitation initiating shape oscillations, allowing viscosity measurement of the liquid melts based on the damping rate of the oscillating droplet. We experimentally investigate the impact of convection on the droplet's damping behavior. The effective viscosity arises and increases as the internal convective flow becomes transitional or turbulent, up to 2-8 times higher than the intrinsic molecular viscosity. The enhanced effective viscosity decays when the stirring has stopped, and an overshoot decay pattern is identified at higher Reynolds numbers, which presents a faster decay rate as the constraint of flow domain size becomes influential. By discriminating the impact of convection on the viscosity results, the intrinsic viscosity can be evaluated with improved measurement accuracy., (© 2021. The Author(s).)

Electromagnetic levitation experiments in space are an essential tool for thermophysical property measurement and solidification studies. In light of the need for material properties as inputs to industrial process modeling, investigators need new tools for efficient experiment planning. MHD surrogate modeling is a parametric method for prediction of flow conditions during processing using the ISS-EML facility. Flow conditions in model Au, Zr, and Ti 39.5 Zr 39.5 Ni 21 samples are predicted using the surrogate model. For Au, flow is shown be turbulent in nearly all experimental conditions, making property measurement difficult. For Zr, the flow is turbulent with the heater on and laminar with the heater off, allowing for property measurement during free-cooling experiments only. For TiZrNi, the flow is laminar under all experimental conditions, indicating that TiZrNi is an excellent candidate for EML experiments. This surrogate modeling approach can be easily applied to other materials of interest, enabling investigators to choose materials that will perform well in levitation and to tailor experiment parameters to achieve desirable flow conditions., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2020.)

The relationship between the excess volume and the structure of Fe-Cr-Ni melts is investigated using containerless levitation and in situ high-energy synchrotron x-ray diffraction techniques. The density of six hypoeutectic Fe-Cr-Ni alloys along the 72 wt. % Fe isopleth was measured in the stable and undercooled regions, and the excess volume was evaluated as a function of Cr concentration. It is found that the 72Fe-Cr-Ni alloys exhibit a positive sign of excess volume and the amount increases with increasing Cr concentration. Analysis of the structure factor and pair distribution function of the alloy family reveals that the short-range order in the melt becomes more pronounced with decreasing Cr concentration; this demonstrates a direct correlation between the excess volume and local liquid structure. A characteristic signature of the icosahedral structure is observed in the structure factor of the melts, and the potential origin of the positive excess volume of the 72Fe-Cr-Ni alloys is qualitatively discussed in relation to the icosahedral structure.

Background: Anatomic variation in the relationship between the lumbar spine and sacrum was first described in the literature nearly a century ago and continues to play an important role in spine deformity, low back pain (LBP), and pelvic trauma. This review will focus on the clinical and surgical implications of abnormal lumbosacral anatomy in the context of sacroiliac joint (SIJ) disease, spine deformity, and pelvic trauma., Methods: A PubMed search using the keywords "lumbosacral transitional vertebrae," "LSTV," "transitional lumbosacral vertebrae," "TLSV," and "sacral dysmorphism" was performed. The articles presented here were evaluated by the authors., Clinical Significance: The prevalence of LSTV varies widely in the literature from 3.9-% to 35.6% in the spine literature, and sacral dysmorphism is described in upwards of 50% of the population in the trauma literature. The relationship between LSTV and LBP is well established. While there is no agreed-on etiology, the source of pain is multifactorial and may be related to abnormal biomechanics and alignment, disc degeneration, and arthritic changes., Surgical Implications: Understanding abnormal lumbosacral anatomy is crucial for preoperative planning of SIJ fusion, spine deformity, and pelvic trauma surgery. LSTV can alter spinopelvic parameters crucial in planning spine deformity correction. Traditional safe zones for sacroiliac screw placement do not apply in the first sacral segment in sacral dysmorphism and risk iatrogenic nerve injury., Conclusions: LSTV and sacral dysmorphism are common anatomic variants found in the general population. Abnormal lumbosacral anatomy plays a significant role in clinical evaluation of LBP and surgical planning in SIJ fusion, spine deformity, and pelvic trauma. Further studies evaluating the influence of abnormal lumbosacral anatomy on LBP and surgical technique would help guide treatment for these patients., Competing Interests: Disclosures and COI: Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted work. This paper is exempt from institutional review board review, as it is not human subjects research. There was no external source of funding for this study., (©International Society for the Advancement of Spine Surgery 2020.)

Thermophysical properties of Fe-Cr-Ni melts are studied using electrostatic levitation and rapid solidification techniques. Six hypoeutectic Fe 0.72 Cr w Ni (0.28- w ) alloys with a Cr/Ni ratio of around 0.8 were melted and solidified at different degrees of undercooling. From the observed relationship between the undercooling and thermal plateau time, the hypercooling limit and heat of fusion of Fe 0.72 Cr w Ni (0.28- w ) melts are determined as a function of Cr mass fraction. A ratio of specific heat and total hemispherical emissivity of the Fe-Cr-Ni melts is calculated using the time-temperature profiles. A new method is presented to evaluate the temperature dependence of specific heat for undercooled melts and applied to this alloy family.

Electromagnetic levitation techniques are used in a microgravity environment to allow materials research under containerless conditions while limiting the influence of gravity. The induced advective flow inside a levitated molten alloy droplet is a key factor affecting solidification phenomena while potentially influencing the measurement of thermophysical properties of metallic alloy. It is thus important to predict the flow velocity under various operation conditions during melt processing. In this work, a magnetohydrodynamic model is applied over the range of conditions under which electromagnetically levitated droplets are processed to represent the maximum flow velocity and shear rate as a polynomial function of heating voltage, density, viscosity, and electrical conductivity of molten materials. An example is given for the ternary steel alloy Fe-19Cr-21Ni (at%) to demonstrate how internal advection under different heater settings becomes a strong function of alloy temperature and is a determining factor in the transition from laminar to turbulent flow conditions. The results are directly applicable to a range of other materials with properties in the range considered, including Ni-based superalloys, Ti-6Al-4V, and many other commercially-important alloys., Competing Interests: D.M.M is the recipient of a NASA award funding collaborations for this investigation as well as support of other research projects funded by the agency; X.X. is a postdoctoral scholar employed under this grant. R.W.H. is the recipient of a NASA award funding collaborations for this investigation as well as support of other research projects funded by the agency; J.L. was previously partially funded under both grants. The authors declare no competing interests.

Ternary Fe-Cr-Ni stainless steel alloys often exhibit a multi-step transformation known as double recalescence where primary ferrite converts to austenite during rapid solidification processes such as casting and welding. In addition to the volume free energy associated with undercooling between the phases, the free energy driving the transformation comes from two additional sources that are retained within the metastable solid-one from the primary phase undercooling and one from melt shear. A new physical model is proposed based on accumulation of defects, such as dislocations or tilt boundaries, and lattice strain. A dimensionless analysis technique shows that the free energy associated with metastable solidification is conserved and the contribution from melt shear can be predicted based on a modification of the Read-Shockley dislocation energy equation. With these additional terms the incubation time between nucleation events becomes inversely proportional to the total free energy squared for bulk diffusion and cubed for grain boundary diffusion mechanisms. In the case of the ferrous alloys studied, the grain boundary mechanism provides a better fit and when the model is applied the delay time behavior collapses to a single master-curve for the entire alloy family., Competing Interests: The author declares no competing interests.

A new hypothesis has been developed to explain the effect of internal fluid flow on the lifetime of a metastable phase in solidifying Fe-Cr-Ni alloys. The hypothesis shows excellent agreement with available experimental results, but microgravity experiments are required for complete validation. Certain Fe-Cr-Ni stainless steel alloys solidify from an undercooled melt by a two-step process in which the metastable ferrite phase forms first followed by the stable austenite phase. Recent experiments using containerless processing techniques have shown that the lifetime of the metastable phase is strongly influenced by flow within the molten sample. Simulations using a commercial computational fluid dynamics (CFD) package, FIDAP, were performed to determine the time required for collision of dendrites and compared to experimental delay time. If the convective velocities are strong enough to bend the primary arms, then the secondary arms of adjacent dendrites can touch. The points of collision form low-angle boundaries and result in high-energy sites that can serve as nuclei for the transformation to the stable phase. It has been determined that the convective velocities in electrostatic levitation (ESL) are not strong enough to cause collision. However, in ground-based electromagnetic levitation (EML), the convective velocities are strong enough to cause the dendrites to deflect so that the secondary arms of adjacent dendrites collide. There is quantitative agreement between the numerically determined time to collision and the experimentally observed delay time in EML. The strong internal velocity due to convection within the EML samples is the reason for the observed difference in delay times between ESL and EML. Microgravity testing is essential because the significant change in nucleation behavior occurs between the ranges accessible by ground-based ESL and EML. Testing in microgravity using EML will permit a large range of internal convective velocities including those that are inaccessible in 1 g.

The delay between conversion of metastable ferrite to stable austenite during ternary Fe-Cr-Ni alloy double recalescence is seen to differ by over an order of magnitude for tests conducted using electrostatic and electromagnetic levitation. Several possible reasons for this deviation are proposed. Thermodynamic calculations on evaporation rates indicate that potential composition shifts during testing are minimized by limiting test time and thermal history. Simulation indicates that deviation would be limited to a factor of 1.5 under worst-case conditions. Possible effects due to differences in sample size are also eliminated since the metastable array, where stable phase nucleation must occur, is significantly smaller than the sample. Differences in internal convection are seen to be the most probable reason for the observed deviation.

Different containerless processing techniques have different strengths and weaknesses. Applying more than one technique allows various parts of a problem to be solved separately. For two research projects, one on phase selection in steels and the other on nucleation and growth of quasicrystals, a combination of experiments using electrostatic levitation (ESL) and electromagnetic levitation (EML) is appropriate. In both experiments, convection is an important variable. The convective conditions achievable with each method are compared for two very different materials: a low-viscosity, high-temperature stainless steel, and a high-viscosity, low-temperature quasicrystal-forming alloy. It is clear that the techniques are complementary when convection is a parameter to be explored in the experiments. For a number of reasons, including the sample size, temperature, and reactivity, direct measurement of the convective velocity is not feasible. Therefore, we must rely on computation techniques to estimate convection in these experiments. These models are an essential part of almost any microgravity investigation. The methods employed and results obtained for the projects levitation observation of dendrite evolution in steel ternary alloy rapid solidification (LODESTARS) and quasicrystalline undercooled alloys for space investigation (QUASI) are explained.

Purpose: The purpose of this review is to determine whether incentive-based programs conducted at worksites increase participation and long-term smoking cessation rates., Methods: Published studies of workplace smoking cessation programs involving incentives and competition were identified through all available years up to winter of 1992 in MEDLINE (1966-1992), Psychlit (1967-1992), Smoking and Health (1960-1992), and Combined Health Information (1973-1992) computer databases and article reference lists. Programs were considered incentive programs when they involved either cash or other prizes paid to the participant for quitting smoking. Incentive competition programs typically involve groups contesting for prizes by having the greatest smoking cessation rates. Thirty studies were found, out of which 15 quasi-experimental and experimental studies are reviewed. The 15 studies that did not have comparison groups were excluded from this report., Results: Only eight studies had a comparison group in which the effects of incentives and competition were separated from the effects of other interventions. Only one study separated the effects of competition from incentives. Five of these studies evaluated smoking rates after six months, and three after 12 months from the program start. Three of these studies showed that incentives increased participation rates, and five enhanced smoking reduction. No study showed, however, that incentives and/or competition enhanced smoking cessation past six months., Conclusions: It appears that incentives/competition may be useful for increasing participation and smoking reduction. Further research needs to be conducted to determine whether incentives and/or competition enhance long-term quit rates, and what are the most effective types of incentive procedures.