Optical microscopy imaging of the thermally-induced spin transition and isothermal multi-stepped relaxation in a low-spin stabilized spin-crossover material.

The thermal spin transition and the photo-induced high-spin → low-spin relaxation of the prototypical [Fe(ptz)6](BF4)2 spin-crossover compound (ptz = 1-propyltetrazole) diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2, which stabilizes the Fe(II) low-spin state, have been investigated. We demonstrate the presence of a crystallographic phase transition around 145 K (i.e. from the high-temperature ordered high-spin phase to a low-temperature disordered low-spin phase) upon slow cooling from room temperature. This crystallographic phase transition is decoupled from the thermal spin transition. A supercooled ordered low-spin phase is observed as in the pure Fe(II) analogue upon fast cooling. A similar order-disorder phase transition is also observed for pure [Ru(ptz)6](BF4)2 but at relatively higher temperature (i.e. at around 150 K) without involving any spin transition. For Ru-diluted [Fe(ptz)6]2+, the crystallographic phase transition as well as strong cooperative effects involving various degrees of elastic frustration are at the origin of stepped sigmoidal high-spin → low-spin relaxation curves, which are modelled in the framework of a classical mean field model, considering both the tunnelling and thermally activated regimes. Optical microscopy studies performed on two different single crystals showed the existence of hysteretic thermal transitions with slight domain formation, hardly visible in the static crystal images. This behavior is attributed to the double effect upon Ru dilution, which decreases the cooperative character of the transition and simultaneously reduces the optical contrast between the LS and HS states. Moreover, the transition temperature revealed to be slightly crystal dependent, highlighting the crucial role of the spatial distribution of Ru from one crystal to another, in addition to the well-known effects of crystal shape and size.

Quantification of Conceptual Model Uncertainty in the Modeling of Wet Deposited Atmospheric Pollutants.

Conceptual model uncertainty and parameter uncertainty are dominant contributors to the total uncertainty of a radioecological model output. In the present study the focus is on conceptual model uncertainty, which is often not acknowledged. Conceptual model uncertainty is assessed by subtracting from the total uncertainty of the model output the propagated parameter uncertainty, obtained by means of Bayesian inference analysis. The conceptual model uncertainty is quantified for two process-based models, which describe the interception of wet deposited pollutants under equilibrium and kinetic conditions, respectively. The natural variability due the chemical valence of the elements considered is accounted for in both models. Quantitative evidence has been obtained that the conceptual model uncertainty can contribute to the total uncertainty budget of the models for interception of wet deposited pollutants at least as much as, if not more than, parameter uncertainty.

Treatment of pediatric multilevel cervical spine fractures in resource-limited settings: a case report.

AIM OF THE STUDY: The main purpose of this study was to highlight the therapeutic approach of pediatric multilevel noncontiguous cervical spine fractures in resource-limited settings. CASE PRESENTATION: We report the case of a 15-year-old teenager with C1, C2, C4, C6, and C7 fractures following fall from height treated with a modified external fixator. At final follow-up, he fully recovered neurologic functions with bone healing. CONCLUSION: The modified external fixator is a therapeutic modality for pediatric multilevel noncontiguous cervical spine fractures.

Early presentation of traumatic cervical disc herniation with neurologic deficit and without an adjacent bone lesion.

AIM OF THE STUDY: The purpose of this study was to explore clinical features and the operational opportunity of traumatic cervical disc herniation. METHOD: Patients with cervical spine injury (413) were retrospectively reviewed. Six patients with neurological deficits were identified to have disc herniation without adjacent bone lesion. The diagnosis was confirmed by MRI. The Japanese Orthopedic Association (JOA) score was used to assess the severity of clinical symptoms. Different grading systems have been used in analyzing various stages of herniated cervical discs. All patients underwent anterior cervical decompression, insertion of autologous iliac crest graft, and fixation with cervical plate. RESULTS: The causes of injury were road traffic accidents in four patients and sport and domestic accidents in one patient each. There were five patients with single intervertebral disc herniation and one patient with double. Pre-operative JOA score was 14 for three patients, the remaining three patients scored 10, 6, and 3 respectively. At final follow-up, the score was 17 for four patients and 14 for two patients. DISCUSSION: Traumatic cervical disc herniation with neurologic deficit and without adjacent bone lesion is a rare condition. MRI is the golden examination to confirm diagnosis. Early recognition is essential for appropriate therapy and to minimize the extent of neurological deficit. CONCLUSION: The MRI is mandatory in diagnosing different types of traumatic herniated cervical disc. Discectomy and anterior cervical interbody fusion using autologous iliac crest graft are the treatment options.

Unprecedented Bistability in Spin-Crossover Solids Based on the Retroaction of the High Spin Low-Spin Interface with the Crystal Bending.

There has been in recent years a continuous increase in spatiotemporal investigations of the dynamics of the first-order transitions in spin-crossover (SCO) solids. In single crystals, this phenomenon proceeds via a single domain nucleation and propagation, characterized in some systems with the presence of two equivalent and symmetric interface orientations, between the high-spin (HS) and low-spin (LS) phases, due to the anisotropic structural change of the unit cell at the transition. The present investigations bring an experimental evidence of the reversible driving of the translational and rotational degrees of freedom of the HS-LS interface. In addition to its rectilinear displacement, the interface rotates between two stable angles, 60o and 120o. It is demonstrated that while the translation motion is accompanied by a crystal's length change, the interface rotation is controlled by the crystal's bending. These results are well-explained in the frame of an elastic theoretical description in which the effect of the crystal bending, on the stability of the interface's orientation, is simulated by applying a moment of forces on the crystal. It is found that the interface orientation becomes unstable beyond a threshold load value, announcing the emergence of a bistability in SCO solids, taking place at constant HS fraction and volume. This work underlines the sensitive character of the interface orientation to any macroscopic crystal bending, an idea that can be used to develop a new generation of robust stress sensors, working at constant volume, thus avoiding deterioration problems due to crystal fatigue.

Elastic Frustration Causing Two-Step and Multistep Transitions in Spin-Crossover Solids: Emergence of Complex Antiferroelastic Structures.

Two-step and multistep spin transitions are frequently observed in switchable cooperative molecular solids. They present the advantage to open the way for three- or several-bit electronics. Despite extensive experimental studies, their theoretical description was to date only phenomenological, based on Ising models including competing ferro- and antiferro-magnetic interactions, even though it is recognized that the elastic interactions are at the heart of the spin transition phenomenon, due to the volume change between the low- and high-temperature phases. To remedy this shortcoming, we designed the first consistent elastic model, taking into account both volume change upon spin transition and elastic frustration. This ingredient was revealed to be powerful, since it was able to obtain all observed experimental configurations in a consistent way. Thus, according to the strength of the elastic frustration, the system may undergo first-order transition with hysteresis, gradual, hysteretic two-step or multistep transitions, and incomplete transitions. Furthermore, the analysis of the spatial organization of the HS and LS species in the plateau regions revealed the emergence of complex antiferro-elastic patterns going from simple antiferro-magnetic-like order to long-range spatial modulations of the high-spin fraction. These results enabled us to identify the elastic frustration as the fundamental mechanism at the origin of the very recent experimental observations showing the existence of organized spatial modulations of the high-spin fraction inside the plateau of two-step spin transitions.

Reversible Control by Light of the High-Spin Low-Spin Elastic Interface inside the Bistable Region of a Robust Spin-Transition Single Crystal.

By using a weak modulated laser intensity we have succeeded in reversibly controlling the dynamics of the spin-crossover (SC) single crystal [{Fe(NCSe)(py)2 }2 (m-bpypz)] inside the thermal hysteresis. The experiment could be repeated several times with a reproducible response of the high-spin low-spin interface and without crystal damage. In-depth investigations as a function of the amplitude and frequency of the excitation brought to light the existence of a cut-off frequency ca. 1.5 Hz. The results not only document the applicability of SC materials as actuators, memory devices, or switches, but also open a new avenue for the reversible photo-control of the spin transition inside the thermal hysteresis.

Structure-driven orientation of the high-spin-low-spin interface in a spin-crossover single crystal.

The orientation of the high-spin (HS)-low-spin (LS) macroscopic interface at the thermal transition of thin [{Fe(NCSe)(py)2}2(m-bpypz)] crystals is explained by considering the possible vanishing of the structural mismatch between the coexisting phases. The structural property which allows mismatch-free interfaces is characterized. The observed orientations of the interface and the tilt angle between the HS and LS domains are accurately reproduced by a two-dimensional continuous medium model, based on the structural data. Simulations using an atomistic electro-elastic model meet the predictions of the macroscopic analysis and provide information on the distribution of the elastic energy density in the biphasic state. The presence of mismatch-free domain structures can explain the exceptional resilience of these crystals upon repeated switching.

Results of radial head resection after Mason type 3 or 4 fracture of the elbow.

BACKGROUND: Resection of the radial head is a surgical indication for comminuted radial head fracture in which internal fixation is inaccessible. Some complications from the surgery can alter the function of the patient's elbow. The objective of this study was to assess functional outcome of the elbow after resection of the radial head. METHODS: A retrospective longitudinal study was performed with patients who underwent radial head resection between 2008 and 2018. Elbow function was assessed by the Mayo Elbow Performance Index (MEPI) for 11 patients comprising three women and eight men. The mean follow-up was 47.6 months. The mean age was 41±10.3 years. RESULTS: Nine patients had a stable and painless elbow. The mean extension-flexion arc was 97.73°±16.03°. The mean values of pronation and supination were 76.8° and 74.5°, respectively. The mean MEPI score was 83.2 points, and restoration of overall function was achieved in 81% of the cases. Poor function was noted in one in 10 that presented with a terrible triad. CONCLUSIONS: Resection of the radial head restored elbow functionality at a rate of 81%, which was a good outcome for patients.

Analysis of consumer behavior for the estimation of the exposure to chemicals in personal care products.

In this study, the main objective was to implement an integrative modelling framework in order to support the prioritization and screening of chemicals present in personal care products (PCPs) regarding their potential to expose users across multiple possible pathways. Here, we implemented an exposure-based framework based on product intake fractions (PiFs) calculated using a two-compartment model reproducing the skin uptake and the competing volatilization of chemicals applied on skin during PCP use. The implemented framework enabled to simultaneously and comprehensively accommodate coupled chemical specific parameters (i.e. physical and chemical properties of the candidate chemicals), exposure information specific for product-chemical combinations, and survey data informing on consumer behavior. A case-study, based on the usage pattern data of 22 PCPs investigated among Swiss individuals (Garcia-Hidalgo et al., 2017a) and 113 candidate chemicals chosen for their suspected presence in the PCP categories of interest was defined to evaluate the applicability of the framework. Nonnegative matrix factorization (NMF) and hierarchical clustering were subsequently applied to identify chemicals with the highest exposure potential and to highlight most relevant mixtures of chemicals on the basis of the specific usage patterns of the considered survey individuals.

Spinal Cord Injury Due to Cervical Disc Herniation without Bony Involvement Caused by Wrestling - A Case Report.

INTRODUCTION: Many cases of cervical spinal disc herniation caused by sporting injury have been reported. Those cases generally accompanied high-energy trauma such as fractures and/or dislocations. The purpose is to present the case of spinal cord injury (SCI) due to cervical disc herniation without bony involvement caused by wrestling. CASE REPORT: We report a case of a 23-year-old man who sustained a cervical SCI during the wrestling competition. He was quadriplegic with no sensory or motor function preserved in sacral segments S4-S5. Conventional radiographs and computed tomography did not reveal bony abnormalities. Magnetic resonance imaging (MRI) showed a free herniated cervical disc severely compressing the spinal cord from central at C3/4 level. He underwent anterior cervical discectomy and interbody fusion using autologous iliac crest bone graft and fixation with the cervical plate. He made an eventful recovery, and 5 years later, he was playing at high competitive level. CONCLUSION: Competitive wrestling-related injuries are quite high. Fortunately, the incidence of SCI among wrestlers is extremely low. Although rare, SCI due to cervical disc herniation without bony involvement is a serious debilitating injury that exerts a devastating effect on a wrestler from a physical, psychological, and socioeconomic point of view, and places an immense burden on society from a public health perspective. The MRI is the golden examination in diagnosing such lesion. The management comprises surgical decompression of neural elements, stabilization, and fusion to provide a higher recovery rate from cord damage to return to play. Wrestler who is completely pain free with full range of motion and strength may be eligible for return to play.

Erecta dislocation of the shoulder joint-A rare injury: About four cases.

A nonresolving axillary nerve injury is a rare associated complication to an inferior dislocation of the shoulder joint. This worsen the midterm outcome of the shoulder. So, neurovascular status must be checked by regular clinical testing and by an electromyography in all cases of inferior dislocation of the shoulder joint.

Interplay between spin-crossover and luminescence in a multifunctional single crystal iron(ii) complex: towards a new generation of molecular sensors.

We present a new example of a mononuclear iron(ii) complex exhibiting a correlated spin-crossover (SCO) transition and strong fluorescence, whose coordination sphere is saturated, for the first time, by six phosphorescent ligands. The interplay between SCO and light emission properties in the thermal region of the spin transition was investigated by means of magnetic, fluorescence, optical absorption and optical microscopy measurements on a single crystal. Overall, the results show an excellent correlation between fluorescence and magnetic data of the present gradual transition, indicating an extreme sensitivity of the optical activity of the ligand to the spin state of the active iron(ii) ions. These results open the way for conceiving new prototypes of pressure and temperature sensors based on this synergy between SCO and luminescence properties. In particular, the fact that cooperative SCO material is not a prerequisite for obtaining such synergetic effects, is useful for the design of thin films or nanoparticles, in which the cooperativity is reduced, for appropriate implementation in nanosized devices to enhance the sensing properties at the nanoscale.

[Fracture-separation of the medial clavicular epiphysis: about 6 cases and review of the literature]. / Fracture-décollement de l'épiphyse médiale de la clavicule: à propos de 6 cas et revue de la littérature.

This study aims to describe the epidemiological characteristics and the different anatomo-clinical entities of the fracture-separation of the medial clavicular epiphysis but also to relate the morphological and functional results of bloody reduction followed by osteosuture using non absorbable thread. Five boys and one girl (mean age 14 years) showed a closed and isolated shoulder girdle trauma. Clinical examination and medical imaging, especially CT scan, allowed the diagnosis of epiphyseal separation and to classify the degree of medial clavicular epiphysiseal ossification indicating the direction of displacement as well as the nature of displacement according to the Salter-Harris classification. Bloody reduction followed by osteosuture using non absorbable thread (No. 1 decimal) was performed in 3 patients. One patient underwent cross-pinning the two younger patients were treated orthopedically. The displacement of the clavicle stump was anterior in 3 patients and retro-sternal in 3 patients. Posterior forms were complicated by odynophagia (n = 2) and asymptomatic compression of the subclavian vein (n = 1). One of the posterior forms was associated with an ipsilateral fracture of the medial one third of the clavicle. Consolidation was achieved in all patients with preservation of shoulder mobility. The fracture-separation of the medial end of the clavicle mimes clinically and radiologically the sternoclavicular dislocation. It can be serious because of the risk of visceral and vascular compression in its posterior form. Tomdensitometry is irreplaceable for an accurate diagnosis. Our preference is for bloody reduction followed by osteosuture using non metallic thread.

Rapid and robust spatiotemporal dynamics of the first-order phase transition in crystals of the organic-inorganic perovskite (C12H25NH3)2PbI4.

The dynamics of the thermally induced first-order structural phase transition in a high-quality single crystal of the organic-inorganic perovskite (C12H25NH3)2PbI4 was investigated by optical microscopy. The propagation of the straight phase front (habit plane) during the phase transition along the cooling and heating pathways of the thermal hysteresis was observed. The thermochromic character of the transition allowed monitoring of the thermal dependence of average optical density and aided the visualization of the interface propagation. The thermal hysteresis loop is 10 K wide, and the interface velocity is constant at V ≈ 1.6 mm s(-1). The transition is accompanied with sizeable change in crystal size, with elongation of ~6% along the b axis and compression of ~ -2% along the a axis, in excellent agreement with previously reported X-ray diffraction data. The progression of the habit plane is at least 160 times faster than in spin-crossover materials, and opens new prospects for organic-inorganic perovskites as solid switching materials. Moreover, the crystals of (C12H25NH3)2PbI4 are unusually mechanically robust and present excellent resilience to thermal cycling. These hitherto unrecognized properties turn this and possibly similar hybrid perovskites into perspective candidates as active medium for microscopic actuation.

Foliar interception of radionuclides in dry conditions: a meta-analysis using a Bayesian modeling approach.

Uncertainty on the parameters that describe the transfer of radioactive materials into the (terrestrial) environment may be characterized thanks to datasets such as those compiled within International Atomic Energy Agency (IAEA) documents. Nevertheless, the information included in these documents is too poor to derive a relevant and informative uncertainty distribution regarding dry interception of radionuclides by the pasture grass and the leaves of vegetables. In this paper, 145 sets of dry interception measurements by the aboveground biomass of specific plants were collected from published scientific papers. A Bayesian meta-analysis was performed to derive the posterior probability distributions of the parameters that reflect their uncertainty given the collected data. Four competing models were compared in terms of both fitting performances and predictive abilities to reproduce plausible dry interception data. The asymptotic interception factor, applicable whatever the species and radionuclide to the highest aboveground biomass values (e.g. mature leafy vegetables), was estimated with the best model, to be 0.87 with a 95% credible interval (0.85, 0.89).

New approach for the assessment of cluster diets.

Dietary risk assessment is a major public health concern, positioned in the context of establishing overall food safety policy. It requires some understanding of population food choices although geographical location and social-cultural environment are variable. Several years ago, a cluster analysis based on FAO consumption data, ranging from 1990 to 1994, was at the origin of the 13, so called, GEMS/Food cluster diets. This analysis required the initial identification of 19 food markers based on geographical and cultural differences. This paper proposes a new modelling of FAO food consumption database in order to define new cluster diets based on updated consumption data from 2002 to 2007 and better adapted statistical methods. Two statistical methods were combined to extract, consumption systems that generate a substructure from the initial food consumption database and then by deriving a clustering of countries according to their consumption system profiles. The clustering resulted in 17 cluster diets composed of 2 up to 30 countries. The few discrepancies between these new clusters and former ones may be due to more recent data, and to the fact that the new approach is based on another mathematical modelling which does not require any initial identification of food markers.