Manganese-rhodium nanoparticles: Adsorption on titanium oxide surfaces and catalyst for syngas reactions.

Manganese-rhodium (Mn-Rh) nanoparticles have emerged as a promising candidate for catalytic applications in the production of syngas, a critical precursor for a wide range of industrial processes. This study employs a comprehensive, theoretical, and computational approach to investigate the structural and electronic properties of Mn-Rh nanoparticles, with a specific focus on their interaction with titanium oxide (TiO2) surfaces and their potential as catalysts for syngas reactions. The density functional theory calculations are employed to explore the adsorption behavior of Mn-Rh nanoparticles on TiO2 surfaces. By analyzing the adsorption energies, geometries, and electronic structure at the nanoscale interface, we provide valuable insights into the stability and reactivity of Mn-Rh nanoparticles when immobilized on TiO2 supports. Furthermore, the catalytic performance of Mn-Rh nanoparticles in syngas production is thoroughly examined. Through detailed reaction mechanism studies and kinetic analysis, we elucidate the role of Mn and Rh in promoting syngas generation via carbon dioxide reforming and partial oxidation reactions. The findings demonstrate the potential of Mn-Rh nanoparticles as efficient catalysts for these crucial syngas reactions. This research work not only enhances our understanding of the fundamental properties of Mn-Rh nanoparticles but also highlights their application as catalysts for sustainable and industrially significant syngas production.

Towards recycling of waste carbon fiber: Strength, morphology and structural features of recovered carbon fibers.

Carbon fiber is one of the most widely used materials in high demand applications due to its high specific properties, however, its post-recycling properties limit its use to low performance applications. In this research, the carbon fiber recovering is examined using two methods: two-step pyrolysis and microwave-assisted thermolysis. The results indicate that the fibers recovered by pyrolysis show reduced surface and structural damage, maintaining the original mechanical properties of the fiber with losses below 5%. The fibers recovered by microwaves undergo significant surface changes that reduce their tensile strength by up to 60% and changes in their graphitic structure, increasing their degree of crystallinity by Raman index ID/IG from 1.98 to 2.86 and their amorphous degree by ID"/IG ratio from 0.411 to 1.599. Recovering fibers from microwave technique is 70% faster compared to two step pyrolysis, and provides recycled fibers with superior surface activation with the presence of polar functional groups -OH, -CO, and -CH that react with the epoxy matrix. The thermal, morphological, structural and mechanical characterizations of the recovered fibers detailed in this work provide valuable findings to evaluate their direct reuse in new composite materials.

Consensus statement: summary of the Quebec Lung Cancer Network recommendations for prioritizing patients with thoracic cancers in the context of the COVID-19 pandemic.

Background: The emergence of covid-19 has the potential to change the way in which the health care system can accommodate various patient populations and might affect patients with non-covid-19 problems. The Quebec Lung Cancer Network, which oversees thoracic oncology services in the province of Quebec under the direction of the Ministère de la Santé et des Services sociaux, convened to develop recommendations to deal with the potential disruption of services in thoracic oncology in the province of Quebec. The summary provided here has been adapted from the original document posted on the Programme québécois du cancer Web site at: https://www.msss.gouv.qc.ca/professionnels/documents/coronavirus-2019-ncov/PJ1_Recommandations_oncologie-thoracique-200415.pdf. Methods: Plans to optimize the health care system and potentially to prioritize services were discussed with respect to various levels of activity. For each level-of-activity scenario, suggestions were made for the services and treatments to prioritize and for those that might have to be postponed, as well as for potential alternatives to care. Results: The principal recommendation is that the cancer centre executive committee and the multidisciplinary tumour board always try to find a solution to maintain standard-of-care therapy for all patients with thoracic tumours, using novel approaches to treatment and the adoption of a network approach to care, as needed. Conclusions: The effect of the covid-19 pandemic on the health care system remains unpredictable and requires that cancer teams unite and offer the most efficient and innovative therapies to all patients under the various conditions that might be forced upon them.

In situ evidence of thermally induced rock breakdown widespread on Bennu's surface.

Rock breakdown due to diurnal thermal cycling has been hypothesized to drive boulder degradation and regolith production on airless bodies. Numerous studies have invoked its importance in driving landscape evolution, yet morphological features produced by thermal fracture processes have never been definitively observed on an airless body, or any surface where other weathering mechanisms may be ruled out. The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission provides an opportunity to search for evidence of thermal breakdown and assess its significance on asteroid surfaces. Here we show boulder morphologies observed on Bennu that are consistent with terrestrial observations and models of fatigue-driven exfoliation and demonstrate how crack propagation via thermal stress can lead to their development. The rate and expression of this process will vary with asteroid composition and location, influencing how different bodies evolve and their apparent relative surface ages from space weathering and cratering records.

Surgical Treatment of a Medial Clavicle Fracture Nonunion with Medial Clavicle Resection and Stabilization to the Sternum with Palmaris Longus Graft.

Medial end clavicular fractures are a rare occurrence. While most of these fractures can be appropriately managed with a nonoperative treatment, some cases of symptomatic nonunion might be surgically addressed to preserve sternoclavicular joint stability and ensure favorable outcomes. The open reduction and osteosynthesis procedure is a commonly performed procedure to treat clavicular fracture nonunion. However, few revision procedures have been described to address the occasional cases of hardware failure or recurrent nonunion of the medial end. In this report, the authors present a case of symptomatic nonunion of the medial clavicle initially treated with osteosynthesis. Implant failure with hardware migration was then treated by medial clavicle resection and stabilization to the sternum using a palmaris longus autograft and the figure-of-eight lacing technique. Excellent functional outcomes at three years of follow-up were obtained. To the authors' knowledge, this is the first case reporting on a sternoclavicular stabilization with a tendon autograft for such an important bone deficit.

Adherence to guidelines in requesting Oncotype DX in a publicly funded health care system.

Background: Oncotype dx [odx (Genomic Health, Redwood City, CA, U.S.A.)] is an approved prognostic tool for women with node-negative, hormone receptor-positive, her2-negative breast cancer. Because of cost, optimal use of this test is crucial, especially in a publicly funded health care system. We evaluated adherence with our provincial guidelines for odx requests, the management of patients with an intermediate recurrence score (rs), and the cost impact of odx. Methods: This retrospective study included 201 consecutive patients with an odx request from two university institutions in Quebec between May 2012 and December 2014. Concordance with provincial guidelines was estimated, with its 95% confidence interval (ci). For patients with an intermediate rs, factors influencing the final treatment decision were assessed. The cost impact of odx was derived from the proportion of patients for whom chemotherapy was not recommended. Results: In 93.0% of patients (95% ci: 89.5% to 96.6%), odx was ordered according to guidelines. The concordance was similar in both institutions (92.7%; 95% ci: 88.1% to 97.3%; and 93.6%; 95% ci: 88.2% to 99.0%). In 112 (55.7%), 78 (38.8%), and 9 (4.5%) patients, the rs suggested low, intermediate, and high risk respectively. In the intermediate-risk group, most patients (n = 58, 74.4%) did not receive chemotherapy, mainly because of patient preference and the absence of a clear proven benefit. Savings of CA$100,000 for the study period (2.5 years) were estimated to be associated with odx use. Conclusions: In our experience, the use of odx was concordant with published recommendations and had a positive cost impact.

Geophysical imaging reveals topographic stress control of bedrock weathering.

Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from three landscapes. The base of the fracture-rich zone mirrors surface topography where the ratio of horizontal compressive tectonic stresses to near-surface gravitational stresses is relatively large, and it parallels the surface topography where the ratio is relatively small. Three-dimensional stress calculations predict these results, suggesting that tectonic stresses interact with topography to influence bedrock disaggregation, groundwater flow, chemical weathering, and the depth of the "critical zone" in which many biogeochemical processes occur.

Magnetic therapeutic delivery using navigable agents.

For treating cancer in particular, therapeutic agents have evolved in complexity in an effort to enhance targeting efficacy. So far, efforts towards the synthesis alone of new therapeutics have attracted most attention. However, present cancer treatments frequently fail because of severe side effects related to the fact that the drug accumulates in insufficient concentration at the tumor site, while being distributed over healthy tissues and organs. More recently, advanced engineering principles have been considered for the development of platforms and drug-loaded vehicles to deliver payloads to the area to be treated by navigating them using the most direct route in order to improve tumor killing effects while minimizing toxic side effects caused by drug activity in nontargeted regions. If the introduction of engineering and principles of robotics to provide complementary techniques in targeted cancer therapy prove to be beneficial, it could influence future delivery methods and the synthesis of therapeutic carriers.

Accurate positioning of magnetic microparticles beyond the spatial resolution of clinical MRI scanners using susceptibility artifacts.

Susceptibility-based negative contrast in magnetic resonance imaging (MRI) provides a mean to visualize magnetic microparticles. In the presence of a number of microparticles in the field of view (FOV), the shape of the artifact is affected by the dipole-dipole interaction between the particles. Due to the limited spatial resolution of the clinical MR scanners, the exact positioning of the particles in MR images is not possible. However, the shape of the artifact can shed light on how the particles are distributed within the FOV. In this work, a simulation model and in-vitro experiments were used to study the shape and the amount of the susceptibility artifact for various spacing and angulations between the microparticles. The results showed that for a pair of identical particles with a diameter of D, the signal loss starts to change when particles are separated ~15 × D and they become fully distinguishable when their distance reaches ~ 40 × D.

MRI visualization of a single 15 µm navigable imaging agent and future microrobot.

In magnetic resonance imaging (MRI), the susceptibility-based contrast provides a way to amplify the effects of a magnetic microparticle, whereas its volume is largely inferior to the spatial resolution of the system. This concept presents an approach to visualization by means of susceptibility artifact using ferromagnetic microparticles. In this work, the amount of the susceptibility artifact was investigated using a simulation model and in vitro experiments on stainless steel microspheres measuring 40, 20 and 15 microm in diameter. The results showed that using a clinical MRI system, a single 15 microm microsphere is detectable in gradient-echo scans. The extent of the susceptibility artifact was found to be related to the scan parameters and the particles' sizes. Since the same ferromagnetic microparticle can be used for MRI-based propulsion, these results suggest several potential applications for navigable agents and microrobots involved in therapy, diagnostics, and imaging inside the microvascular network of the human body.

Safety evaluation of magnetic catheter steering with upgraded magnetic resonance imaging system.

Catheter navigation and placement through the arterial network is a major limitation for clinical procedure. In this article, a specific catheter tip and a modified clinical MRI scanner with an upgraded gradient system are used to steer a catheter through a single Y-shaped bifurcation. Safety aspects are analyzed to avoid the peripheral nerve stimulation (PNS) according to an empirical law of magnetostimulation and the magnetic field of upgraded 3D gradient coils. For a rabbit-sized device, the rising time of gradients system have to be limited to 1.7ms at 400mT.m(-1) to avoid PNS. These rise time values allow the use of this system for catheter steering and other more demanding applications.

Integrated circuit-based instrumentation for microchip capillary electrophoresis.

Although electrophoresis with laser-induced fluorescence (LIF) detection has tremendous potential in lab on chip-based point-of-care disease diagnostics, the wider use of microchip electrophoresis has been limited by the size and cost of the instrumentation. To address this challenge, the authors designed an integrated circuit (IC, i.e. a microelectronic chip, with total silicon area of <0.25 cm2, less than 5 mmx5 mm, and power consumption of 28 mW), which, with a minimal additional infrastructure, can perform microchip electrophoresis with LIF detection. The present work enables extremely compact and inexpensive portable systems consisting of one or more complementary metal-oxide-semiconductor (CMOS) chips and several other low-cost components. There are, to the authors' knowledge, no other reports of a CMOS-based LIF capillary electrophoresis instrument (i.e. high voltage generation, switching, control and interface circuit combined with LIF detection). This instrument is powered and controlled using a universal serial bus (USB) interface to a laptop computer. The authors demonstrate this IC in various configurations and can readily analyse the DNA produced by a standard medical diagnostic protocol (end-labelled polymerase chain reaction (PCR) product) with a limit of detection of approximately 1 ng/microl (approximately 1 ng of total DNA). The authors believe that this approach may ultimately enable lab-on-a-chip-based electrophoretic instruments that cost on the order of several dollars.

In vivo MR-tracking based on magnetic signature selective excitation.

A novel magnetic resonance (MR)-tracking method specifically developed to locate the ferromagnetic core of an untethered microdevice, microrobot, or nanorobot for navigation or closed-loop control purpose is described. The tracking method relies on the application of radio-frequency (RF) excitation signals tuned to the equipotential magnetic curves generated by the magnetic signature of the object being tracked. Positive contrast projections are obtained with reference to the position of the magnetic source. A correlation function performed on only one k-space line for each of the three axes and corresponding to three projections, is necessary to obtain a 3-D location of the device. In this study, the effects of the sphere size and the RF frequency offset were investigated in order to find the best contrast noise ratio (CNR) for tracking. Resolution and precision were also investigated by proper measurement of the position of a ferromagnetic sphere by magnetic resonance imaging (MRI) acquisition and by comparing them with the real position. This method is also tested for a moving marker where the positions found by MRI projections were compared with the ones taken with a camera. In vitro and in vivo experiments show the operation of the technique in tortuous phantom and in animal models. Although the method was developed in the prospect of new interventional MR-guided endovascular operations based on miniature untethered devices, it could also be used as a passive tracking method using tools such as catheters or guide wires.

Real-time software platform design for in-vivo navigation of a small ferromagnetic device in a swine carotid artery using a magnetic resonance imaging system.

Using an 1.5T Siemens clinical Magnetic Resonance Imaging system (MRI), a 1.5 mm diameter ferromagnetic bead is moved across a pre-planned path in the carotid artery of a 25 kg living swine. The software architecture for the navigation and path planning is herein described. Using the real-time feedback capabilities of recent MRIs, the device is moved, controlled and tracked using the magnetic gradients coils already present for imaging purposes. Navigation of the ferromagnetic device has been achieved with a peak velocity of about 13 cm/s through a set of pre established 11 waypoints. The dedicated software architecture presented in this paper lies in a modified real-time MRI imaging sequence. The dedicated architecture permits the navigation of the ferromagnetic bead with an operating frequency of 24 Hz Real-time control of the magnetic core is achieved through the implementation of a simple 2D PID controller incorporated in the presented software platform.

Sequence design and software environment for real-time navigation of a wireless ferromagnetic device using MRI system and single echo 3D tracking.

Software architecture for the navigation of a ferromagnetic untethered device in a 1D and 2D phantom environment is briefly described. Navigation is achieved using the real-time capabilities of a Siemens 1.5 T Avanto MRI system coupled with a dedicated software environment and a specially developed 3D tracking pulse sequence. Real-time control of the magnetic core is executed through the implementation of a simple PID controller. 1D and 2D experimental results are presented.

[Diagnosis and classification of pulmonary arterial hypertension]. / Diagnostic et classification des hypertensions artérielles pulmonaires.

The clinical classification of types of pulmonary hypertension has made it possible to better standardize the approach to the diagnosis and treatment of patients, to perform clinical studies among homogeneous patients, and to discover common laboratory abnormalities that may serve as markers or help elucidate mechanisms of disease. Pulmonary arterial hypertension groups together different diseases that affect the small-caliber pulmonary arteries and lead to a progressive increase in pulmonary arterial resistance and right heart failure. A specific diagnosis of pulmonary arterial hypertension is generally based on a detailed and methodical clinical evaluation. Pulmonary biopsy is rarely indicated. Work-up in a center specialized in the management of this disease is frequently appropriate when the cause of the hypertension is not clear or when a specific treatment is envisaged.

Potential Applications of Untethered Microdevices in the Blood Vessels within the Constraints of an MRI System.

This paper presents potential medical applications that an untethered microdevice in the cardiovascular system could perform within an MRI system. Recent developments and continuing evolution in micro/nano fabrication and design techniques will enable the development of functional microdevices able to explore the cardiovascular system. The Magnetic Resonance Submarine (MR-Sub) project is a first step towards this goal. Magnetic force generated by the gradient coils of an MRI system provides a propulsion mechanism that simplifies miniaturization and bypasses energetic challenges. Untethered microdevices may play an important complementary role in the next generation of minimally invasive tools. A better efficiency and targetability of the treatments will be achieved when microsystems such as the MR-Sub will allow a more extensive access to smaller blood vessels.

Real-time Magnetic Resonance Gradient-based Propulsion of a Wireless Microdevice Using Pre-Acquired Roadmap and Dedicated Software Architecture.

A new method for the propulsion of a spherical ferromagnetic device along a given path in a water filled phantom with no human interaction is presented using an 1.5 T Magnetic Resonance Imaging (MRI) clinical system. A special real time loop is implemented and presented that feeds the scanner with the appropriate gradients amplitudes and directions based on a pre-determined path. This paper studies the necessary propulsion conditions and limitations such as device dimensions and necessary gradient amplitude as well as overall latency problems such as communication delays and computation delays needed to achieve precise propulsion. It also presents a dedicated software environment for path control and validation, propulsion and tracking of such device.

Adapting MRI systems to propel and guide microdevices in the human blood circulatory system.

Magnetic resonance imaging (MRI) systems are widely used to gather noninvasively images of the interior of the human body. This paper suggests that an MRI system can be seen beyond being just a tool for imaging purpose but one that can propel and guide special microdevices in the human body to perform specific medical tasks. More specifically, an MRI system can potentially be used to image the region of interest, propel a microdevice through the generation of magnetic gradients, determine the location of the device, compute the corrective actions through feedback control algorithms and adjust the generation of the magnetic gradients accordingly to navigate such a microdevice in a preplanned path. This paper presents an introductory description of the proposed techniques, the main issues to consider, and some preliminary data indicating the validity of this approach.

Microdevice's susceptibility difference based MRI positioning system, a preliminary investigation.

A positioning technique for an endovascular microdevice propelled by magnetic force inside a magnetic resonance imaging (MRI) system is being developed. Positioning options are presented and a magnetic positioning technique is described in more details. Since a magnetic positioning system is deeply dependent on the quality of the measurement modality, we describe the main magnetic field measurement techniques that can be used inside an MRI. Finally, we propose a magnetic positioning system using MRI phase images to measure the magnetic distortion induced by the ferromagnetic body. Positioning results on a 1010/1020 carbon steel, 1.5875 mm diameter sphere with gradient echo phase images are presented.