Towards Room Temperature Thermochromic Coatings with controllable NIR-IR modulation for solar heat management & smart windows applications.

Solar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) - T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness' control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5-37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input.

Room temperature bio-engineered multifunctional carbonates for CO2 sequestration and valorization.

This contribution reports, for the first time, on an entirely green bio-engineering approach for the biosynthesis of single phase crystalline 1-D nano-scaled calcite CaCO3. This was validated using H2O as the universal solvent and natural extract of Hyphaene thebaica fruit as an effective chelating agent. In this room temperature green process, CaCl2 and CO2 are used as the unique source of Ca and CO3 respectively in view of forming nano-scaled CaCO3 with a significant shape anisotropy and an elevated surface to volume ratio. In terms of novelty, and relatively to the reported scientific and patented literature in relation to the fabrication of CaCO3 by green nano-chemistry, the current cost effective room temperature green process can be singled out as per the following specificities: only water as universal solvent is used, No additional base or acid chemicals for pH control, No additional catalyst, No critical or supercritical CO2 usage conditions, Only natural extract of thebaica as a green effective chelating agent through its phytochemicals and proper enzematic compounds, room Temperature processing, atmospheric pressure processing, Nanoscaled size particles, and Nanoparticles with a significant shape anisotropy (1-D like nanoparticles). Beyond and in addition to the validation of the 1-D synthesis aspect, the bio-engineered CaCO3 exhibited a wide-ranging functionalities in terms of highly reflecting pigment, an effective nanofertilizer as well as a potential binder in cement industry.

Binary vanadium pentoxide carbon-graphene foam composites derived from dark red hibiscus sabdariffa for advanced asymmetric supercapacitor.

The development of advanced electrode materials derived from biomass for the next generation of energy storage devices, such as supercapacitors with high specific energy and specific power coupled with a good cycle stability, is required to meet the high demand for electric vehicles and portable devices. In this study, sustainable binary vanadium pentoxide carbon-graphene foam composites (V2O5@C-R2HS/GF) were synthesized using a solvothermal method. The X-ray diffraction, Raman and FTIR techniques were used to study the structural properties of the composites (V2O5@C-R2HS/20 mg GF and V2O5@C-R2HS/40 mg GF). The SEM micrographs displayed an accordion-like morphology resulting from the graphene foam-modified V2O5@C-R2HS composite. The V2O5@C-R2HS, V2O5@C-R2HS/20 mg GF and V2O5@C-R2HS/40 mg GF composites were evaluated in a three-electrode configuration using 6 M potassium hydroxide (KOH) as an aqueous electrolyte. Furthermore, a two-electrode device was carried out by fabricating an asymmetric device (V2O5@C-R2HS/GF//AC) where V2O5@C-R2HS/20 mg GF was used as a positive electrode and activated carbon (AC) as a negative electrode at a cell voltage of 1.6 V in 6 M KOH. The V2O5@C-R2HS/GF//AC showed a high specific energy and specific power values of 55 W h kg-1 and 707 W kg-1, respectively, at a specific current of 1 A g-1. The asymmetric device presented a good stability test showing 99% capacity retention up to 10 000 cycles and was confirmed by the floating time up to 150 h with specific energy increasing 23.6% after the first 10 h. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

2.5 TW, two-cycle IR laser pulses via frequency domain optical parametric amplification.

Broadband optical parametric amplification in the IR region has reached a new milestone through the use of a non-collinear Frequency domain Optical Parametric Amplification system. We report a laser source delivering 11.6 fs pulses with 30 mJ of energy at a central wavelength of 1.8 µm at 10 Hz repetition rate corresponding to a peak power of 2.5 TW. The peak power scaling is accompanied by a pulse shortening of about 20% upon amplification due to the spectral reshaping with higher gain in the spectral wings. This source paves the way for high flux soft X-ray pulses and IR-driven laser wakefield acceleration.

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches.

The modulated scattering technique is based on the use of reconfigurable electromagnetic scatterers, structures able to scatter and modulate an impinging electromagnetic field in function of a control signal. The modulated scattering technique is used in a wide range of frequencies up to millimeter waves for various applications, such as field mapping of circuits or antennas, radio-frequency identification devices and imaging applications. However, its implementation in the terahertz domain remains challenging. Here, we describe the design and experimental demonstration of the modulated scattering technique at terahertz frequencies. We characterize a modulated scatterer consisting in a bowtie antenna loaded with a vanadium dioxide switch, actuated using a continuous current. The modulated scatterer behavior is demonstrated using a time domain terahertz spectroscopy setup and shows significant signal strength well above 0.5 THz, which makes this device a promising candidate for the development of fast and energy-efficient THz communication devices and imaging systems. Moreover, our experiments allowed us to verify the operation of a single micro-meter sized VO2 switch at terahertz frequencies, thanks to the coupling provided by the antenna.

Metal-Insulator Transition of strained SmNiO3 Thin Films: Structural, Electrical and Optical Properties.

Samarium nickelate (SmNiO3) thin films were successfully synthesized on LaAlO3 and SrTiO3 substrates using pulsed-laser deposition. The Mott metal-insulator (MI) transition of the thin films is sensitive to epitaxial strain and strain relaxation. Once the strain changes from compressive to tensile, the transition temperature of the SmNiO3 samples shifts to slightly higher values. The optical conductivity reveals the strong dependence of the Drude spectral weight on the strain relaxation. Actually, compressive strain broadens the bandwidth. In contrast, tensile strain causes the effective number of free carriers to reduce which is consistent with the d-band narrowing.

Assessing the effectiveness of sustainable land management policies for combating desertification: A data mining approach.

This study investigates the relationship between fine resolution, local-scale biophysical and socioeconomic contexts within which land degradation occurs, and the human responses to it. The research draws on experimental data collected under different territorial and socioeconomic conditions at 586 field sites in five Mediterranean countries (Spain, Greece, Turkey, Tunisia and Morocco). We assess the level of desertification risk under various land management practices (terracing, grazing control, prevention of wildland fires, soil erosion control measures, soil water conservation measures, sustainable farming practices, land protection measures and financial subsidies) taken as possible responses to land degradation. A data mining approach, incorporating principal component analysis, non-parametric correlations, multiple regression and canonical analysis, was developed to identify the spatial relationship between land management conditions, the socioeconomic and environmental context (described using 40 biophysical and socioeconomic indicators) and desertification risk. Our analysis identified a number of distinct relationships between the level of desertification experienced and the underlying socioeconomic context, suggesting that the effectiveness of responses to land degradation is strictly dependent on the local biophysical and socioeconomic context. Assessing the latent relationship between land management practices and the biophysical/socioeconomic attributes characterizing areas exposed to different levels of desertification risk proved to be an indirect measure of the effectiveness of field actions contrasting land degradation.

Alternative nano-structured thin-film materials used as durable thermal nanoimprint lithography templates.

Nanoimprint templates made of diamond-like carbon (DLC) and amorphous silicon carbide (SiC) thin films and fluorine-doped associated materials, i.e. F-DLC and F-SiC were investigated in the context of thermal nanoimprint lithography (NIL) with respect to their release properties. Their performances in terms of durability and stability were evaluated and compared to those of conventional silicon or silica molds coated with antisticking molecules applied as a self-assembled monolayer. Plasma-enhanced chemical vapor deposition parameters were firstly tuned to optimize mechanical and structural properties of the DLC and SiC thin films. The impact of the amount of fluorine dopant on the deposited thin films properties was then analyzed. A comparative analysis of DLC, F-DLC as well as SiC and F-SiC molds was then carried out over multiple imprints, performed into poly (methyl methacrylate) (PMMA) thermo-plastic resist. The release properties of un-patterned films were evaluated by the measurement of demolding energies and surface energies, associated with a systematic analysis of the mold surface contamination. These analyses showed that the developed materials behave as intrinsically easy-demolding and contamination-free molds over series of up to 40 imprints. To our knowledge, it is the first time that such a large number of imprints has been considered within an exhaustive comparative study of materials for NIL. Finally, the developed materials went through standard e-beam lithography and plasma etching processes to obtain nanoscale-patterned templates. The replicas of those patterned molds, imprinted into PMMA, were shown to be of high fidelity and good stability after several imprints.

Fabrication of high aspect ratio tungsten nanostructures on ultrathin c-Si membranes for extreme UV applications.

In this work, we demonstrate a full process for fabricating high aspect ratio diffraction optics for extreme ultraviolet lithography. The transmissive optics consists in nanometer scale tungsten patterns standing on flat, ultrathin (100 nm) and highly transparent (>85% at 13.5 nm) silicon membranes (diameter of 1 mm). These tungsten patterns were achieved using an innovative pseudo-Bosch etching process based on an inductively coupled plasma ignited in a mixture of SF6 and C4F8. Circular ultra-thin Si membranes were fabricated through a state-of-the-art method using direct-bonding with thermal difference. The silicon membranes were sputter-coated with a few hundred nanometers (100-300 nm) of stress-controlled tungsten and a very thin layer of chromium. Nanoscale features were written in a thin resist layer by electron beam lithography and transferred onto tungsten by plasma etching of both the chromium hard mask and the tungsten layer. This etching process results in highly anisotropic tungsten features at room temperature. The homogeneity and the aspect ratio of the advanced pattern transfer on the membranes were characterized with scanning electron microscopy after focus ion beam milling. An aspect ratio of about 6 for 35 nm size pattern is successfully obtained on a 1 mm diameter 100 nm thick Si membrane. The whole fabrication process is fully compatible with standard industrial semiconductor technology.

Evaluation and selection of indicators for land degradation and desertification monitoring: methodological approach.

An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.

Evaluation and selection of indicators for land degradation and desertification monitoring: types of degradation, causes, and implications for management.

Indicator-based approaches are often used to monitor land degradation and desertification from the global to the very local scale. However, there is still little agreement on which indicators may best reflect both status and trends of these phenomena. In this study, various processes of land degradation and desertification have been analyzed in 17 study sites around the world using a wide set of biophysical and socioeconomic indicators. The database described earlier in this issue by Kosmas and others (Environ Manage, 2013) for defining desertification risk was further analyzed to define the most important indicators related to the following degradation processes: water erosion in various land uses, tillage erosion, soil salinization, water stress, forest fires, and overgrazing. A correlation analysis was applied to the selected indicators in order to identify the most important variables contributing to each land degradation process. The analysis indicates that the most important indicators are: (i) rain seasonality affecting water erosion, water stress, and forest fires, (ii) slope gradient affecting water erosion, tillage erosion and water stress, and (iii) water scarcity soil salinization, water stress, and forest fires. Implementation of existing regulations or policies concerned with resources development and environmental sustainability was identified as the most important indicator of land protection.

[Primary meningococcal B osteomyelitis and arthritis with multifocal pyomyositis in a child: a case report]. / Ostéoarthrite de hanche primitive et myosite multifocale à méningocoque B chez un enfant de 7 ans.

Neisseria meningitidis is associated with severe invasive infections such as meningitis and fulminant septicemia. Septic arthritis due to N. meningitidis is rare and bone infections have been reported exceptionally. We report the case of a 7-year-old boy who presented with septic arthritis of the right hip associated with a septic location on the pelvis and pyomyositis of the adjacent muscle. Culture of the joint fluid was sterile but universal 16S polymerase chain reaction (PCR) of this fluid revealed group B N. meningitidis. Our patient had never presented any symptoms of meningitis or septicemia and blood cultures were all sterile. Despite appropriate antibiotic treatment, the course of the disease was unusually long and his status did not improve until surgical lavage of the hip was performed. Moreover, MRI imaging showed bilateral hypersignals of the adjacent muscles and revealed an abscess formation in the left gluteus maximus muscle. Presumptive diagnosis bacterial myositis was confirmed by an elevation of creatine phosphokinase in the sera up to 21-fold the normal value but the culture of the abscess, performed 10 days after initiation of antibiotics, was sterile. Despite an initially unfavorable course, this patient's status improved after surgical drainage and he fully recovered 1 month later. This observation illustrates an unusual presentation of invasive meningococcal infection. The respective roles of infection and an inflammatory phenomenon during the course of the disease are discussed. Moreover, this case emphasizes the value of PCR for bacteriological diagnosis of bone and joint infections.

Second harmonic generation in AlGaAs photonic wires using low power continuous wave light.

We report modal phase matched (MPM) second harmonic generation (SHG) in high-index contrast AlGaAs sub-micron ridge waveguides, by way of sub-mW continuous wave powers at telecommunication wavelengths. We achieve an experimental normalized conversion efficiency of ~14%/W/cm2, obtained through a careful sub-wavelength design supporting both the phase matching requirement and a significant overlap efficiency. Furthermore, the weak anomalous dispersion, robust fabrication technology and possible geometrical and thermal tuning of the device functionality enable a fully integrated multi-functional chip for several critical areas in telecommunications, including wavelength (time) division multiplexing and quantum entanglement.

[Central neurocytoma: three case reports]. / Neurocytome central: à propos de trois observations.

Central neurocytoma is classically recognized as an intraventricular benign brain tumour. Extraventricular localisation is rarer. We report two intraventricular neurocytoma and another bulbar extraventricular neurocytoma. Histologically, central neurocytoma presents remarkable likeness characteristics to oligodendroglioma, but immunohistochemical study distinguishes this tumour. Imaging appearances (CT, MRI) raise the diagnosis and immunohistochemical study confirm it. The purpose of our work is to assess the value of imaging (CT, MRI) in the diagnosis of central neurocytoma.

[Permanent, habitual dislocation and recurrent dislocation of the patella in children: surgical management by patellar ligamentous transfer in 50 knees]. / Traitement chirurgical des luxations et instabilités patellaires chez l'enfant et l'adolescent par transfert ligamento-périosté

PURPOSE OF THE STUDY: Appropriate treatment of patellar dislocation in children and adolescents remains a subject of debate. Ligamentous transfer or "soft rod" is a technique for realigning the extensor mechanism that can be adapted to children. We analyzed results obtained in our patients. MATERIAL AND METHODS: Between 1979 and 2000, 35 children (50 knees) underwent realignment which was combined in all cases with lateral retinacular release and medial reefing using the Insall procedure. Complementary procedures were needed in certain cases (quadriceps lengthening, femoral sulcus plasty, quadriceps release). Mean age at surgery was 11 years, range 5-15 years. All patients were reviewed at skeletal maturity with a mean follow-up of 7.5 years. The last review included a functional assessment using the IKDC form and standard x-rays (anteroposterior and lateral standing view and tangential view at 30 degrees flexion). A computed tomography scan and/or magnetic resonance imaging series were done preoperatively and at last follow-up. DISCUSSION: We distinguished two groups of patients, those with major (permanent or habitual) dislocation of the patella and those with recurrent dislocation. Functional outcome was good in 76% and 86% of knees respectively. There were eight cases of recurrent dislocation: five knees underwent revision surgery with good outcome. The femoral sulcus angle was improved in both groups, but especially in the congenital dislocation group. There was on case of reversed tibial slope (-2 degrees) ant to slopes at 0 degrees. Functional outcome was equivalent to results from earlier series (Grammont, Bensahel, Langeskiold), but comparison was hampered due to the heterogeneous nature of the different series. Femoral sulcus remodeling can enable good patellar stability if the surgery is performed early enough (before age 10 years). In teenagers with major instability, femoral sulcus plasty must be associated with the realignment procedure. We noted a small amplitude reduction of the tibial slope in eleven knees. The procedure appears to have an "epiphysiodesis effect" but with no functional consequence. CONCLUSION: Ligamentous transfer combined with different procedures is a method of choice for stabilizing the extensor system, enabling a normal femoral sulcus angle if the child is operated early. Remodeling of the tibial tuberosity could be related to a transient vascular disorder.

[Role of embolization in renal angiomyolipomas]. / Rôle de l'embolisation dans les angiomyolipomes du rein.

OBJECTIVE: The purpose of this study is to present the role of embolization in the treatment of renal angiomyolipoma (AML) in cases of hemorrhage and to prevent bleeding. METHODS: Over a period of 10 years, 35 AMLs in 34 patients, recruited in two medical centers, were treated with embolization: 16/35 AML were treated urgently to stop bleeding, and 19/35 AML had preventive embolization. Six patients were completely asymptomatic and 13 had a history of previous hematoma or flank pain. Catheterization was highly selective in all cases (coaxial microcatheter in 19 cases), and for embolization we used nonresorbable microparticles, coils, and alcohol. RESULTS: When patients presented with acute bleeding, embolization was efficient in 80% of cases; another embolization was necessary in two cases, and surgery in two others. In six of these cases, surgery was planned and done at a later date. When treatment was preventive, one embolization was necessary in 17 cases, and two embolizations per case were necessary in the other two. Over a period of 18 months of follow-up, we observed a 28% decrease in tumor volume; four patients were treated by surgery at a later date. CONCLUSION: Embolization is the technique of choice to treat a bleeding AML urgently. When preventive treatment is considered, in symptomatic or asymptomatic AML, embolization can be an alternative for surgery, but more data is needed to specify its proper place in the management of these tumors.

[Spinal vascular malformation in a child, revealed by lumbar puncture]. / Malformation vasculaire intraspinale chez l'enfant révélée dans les suites d'une ponction lombaire.

Spinal vascular malformations are exceptional in children. We report a case in 1 year-old patient due to a spinal vascular malformation which was revealed by paraplegia after lumbary punction. The diagnosis was made by MRI. Spontaneous outcome was characterised by the persistence of paraplegia.

[Abdominal polyarteritis nodosa: angiographic features]. / Périartérite noueuse dans sa forme intra abdominale: aspects angiographiques.

PURPOSE: Polyarteritis nodosa (PAN) is a systemic vasculitis of small and medium size arteries. The purpose of this study is to evaluate imaging findings, especially angiographic features, of 17 patients with abdominal involvement from polyarteritis nodosa. PATIENTS AND METHODS: We reviewed the medical records and imaging findings of 17 patients with PAN involving the abdomen. All patients underwent digital subtraction angiography of the renal or visceral arteries completed by a post-angiographic KUB. Abdominal CT scan was available in three patients. All patients underwent muscle biopsy. A surgical biopsy of the gallbladder was obtained in one patient. RESULTS: Multiple small aneurysms involving small and medium sized arteries were detected at angiography in 12 patients. CT showed a renal subcapsular hematoma in two patients and acute pancreatitis in one patient. CONCLUSION: Involvement of gastrointestinal and renal arteries is frequent in polyarteritis nodosa. The diagnosis of PAN should be considered when multiple small-sized aneurysms are present at angiography even if biopsy is negative.

Influence of the laser pulse duration on spectrochemical analysis of solids by laser-induced plasma spectroscopy.

Quantitative analysis of aluminum and copper alloys by means of laser-induced plasma spectroscopy (LIPS) has been investigated for three representative laser pulse durations (80 fs, 2 ps, and 270 ps). The experiments were carried out in air at atmospheric pressure with a constant energy density of 20 J/cm2. Because the decay rate of the spectral emission depends on the laser pulse duration, the optimum detection requires an optimization of the temporal gating acquisition parameters. LIPS calibration (sensitivity and nonlinearity) and the limit of detection (LOD) are discussed in detail. While the LOD of minor elements embedded in alloy samples obtained by sub-picosecond or sub-nanosecond laser pulses are both time and element dependent, provided an appropriate temporal window is chosen, the optimum LODs (several parts per million (ppm)) prove to be independent of the laser pulse duration. Finally, it is found that for elements such as those detected here, gated LIPS spectra using picosecond or sub-picosecond laser pulses provide much better LOD values than non-gated spectra.

Fluid modeling of the laser ablation depth as a function of the pulse duration for conductors.

Laser ablation of an aluminum target as a function of the pulse duration, for fluences up to 30 J/cm(2) and a wavelength of 0.8 microm, is investigated by means of a fluid code. For a given fluence, the ablation depth shows a minimum for a pulse duration of approximately 10 ps between a maximum obtained for pulses shorter than approximately 1 ps and a lower maximum obtained for pulses in the nanosecond range, in qualitative agreement with published experimental results. The decrease in ablation depth with increase in pulse duration observed between 1 and 10 ps results from the reduced temperature rise near the surface due to increased inward heat transport. The increase in the ablation depth above approximately 10 ps is due to the increase in electron density gradient length while the laser pulse intensity is close to maximum, which thus enables the plasma to absorb more of the laser pulse energy for increased ablation.