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Cyclopropylamine borane C3H5NH2BH3 (C3AB), 2-ethyl-1-hexylamine borane CH3(CH2)3CH(C2H5)CH2NH2BH3 (C2C6AB) and didodecylamine borane (C12H25)2NHBH3 ((C12)2AB) are three new amine borane adducts (ABAs). They are synthesized by reaction of the corresponding amines with a borane complex, the reaction being exothermic as shown by Calvet calorimetry. The successful synthesis of each has been demonstrated by FTIR, Raman and NMR. For instance, the 11B NMR spectra show the presence of signals typical of the NBH3 environment, thereby implying the formation of B-N bonds. The occurrence of dihydrogen bonds (DHBs) for each of the ABAs has been highlighted by DSC and FTIR, and supported by DFT calculations (via the Mulliken charges for example). When heated, the three ABAs behave differently: C3AB and C2C6AB decompose from 68 to 100 °C whereas (C12)2AB is relatively stable up to 173 °C. That means that these ABAs are not appropriate as hydrogen carriers, but the 'most' stable (C12)2AB could open perspectives for the synthesis of advanced materials.
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The discovery of a universal memory that exhibits fast access speed, high-density storage, and non-volatility has fuelled research into phase-change materials over the past decades. In spite of the efficiency of the inorganic chalcogenides for phase-change random access memory (PCRAM), they still have some inherent drawbacks, such as high temperature required for phase change and difficulty to control the domain size of the phase change, because of their brittleness. Here we present a AuI -thiolate coordination polymer which undergoes two successive phase changes on application of mild heating (<200 °C) from amorphous-to-crystalline1-to-crystalline2 phases. These transitions are reversible upon soft hand grinding. More importantly, each phase exhibits different photoluminescent properties for an efficient optical read-out. We believe that the ability of the AuI -thiolate coordination polymer to have reversible phase changes under soft conditions and at the same time to display distinct optical signals, can pave the way for the next generation of PCRAM.
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The development of porous films with an accessible high specific surface area is important for designing new adsorbents, sensors, or catalyst supports. Here, we describe a simple method to prepare a silica foam coating using a calcium chloride-assisted evaporation-induced emulsification method. An alcoholic silica sol containing calcium chloride and a poly(ethylene oxide)-based polymer is deposited on a substrate by dipping. The evaporation of the alcohol induces a phase separation between the silica-rich phase and the calcium-rich one. The size of the droplets increases via a coalescence process until the gelation of the sol, which determines the final pore size between 100 nm and 3 µm. Thermal analysis and monitoring of droplet evaporation confirm that the departure of the solvent is delayed by the presence of calcium chloride in the sol. The influence of the nature of the polymer on the porosity is discussed. The use of a block copolymer such as the Pluronic F-127, which strongly stabilizes the emulsion, allows to reach a low pore size (400 nm), while on the contrary, we propose to use a short poly(ethylene glycol) (PEG) such as PEG-400, which weakly stabilizes it, leading to larger pores (2-3 µm). Furthermore, we show that the addition of a zirconium salt (ZrOCl2·8H2O) to the silica sol accelerates the condensation step of the silica and leads to the decrease in the pore size.
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The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn2(NITIm)3]ClO4}n (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm-) are reduced to their diamagnetic aminoxyl form (denoted NITRed2-). Upon cooling, the high-temperature species {[MnII2(NITIm)3]ClO4}n (1HT) turns into the low-temperature species {[MnIII2(NITRed)2(NITIm)]ClO4}n (1LT) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV-vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.
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We present for the first time an original method to elaborate AlN nanofilaments (NFs) by using a preceramic-based electrospinning process. Initially, an Al-containing precursor (poly(ethylimino)alane) is mixed with an organic spinnable polymer to be electrospun and generate polymeric filaments with a homogeneous diameter. A ceramization step at 1000 °C under ammonia and a crystallization step at 1400 °C under nitrogen are performed to get the final product made of AlN NFs with a diameter ranging from 150 to 200 nm. Studies carried out by high resolution electron microscopy and 3D tomography show their regular morphology, with high chemical purity and polycrystalline nature.
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OBJECTIVES: New bioactive materials were introduced to not only restore the lost dental hard tissue but also to release fluoride that inhibits demineralization and occurrence of secondary caries. The current study thus aims to assess Fluoride release as well as the mechanical and physical properties of two new commercially available bioactive restorative materials. METHODS: Two materials, Cention® Forte (CF) (Ivoclar Vivadent), Surefil one™ (SO) (Denstply Sirona), were evaluated in terms of fracture toughness (FT), flexural strength (FS), flexural modulus (FM) (ISO 4049), compressive strength (CS), and Vickers hardness (VH). In addition, thermogravimetric analysis (TGA) was performed, as well as pH measurements and quantification of Fluoride release after immersion in distilled water at times of 0, 7, 14 and 21 days. The sealing ability was evaluated using silver nitrate dye penetration on natural teeth. Finally, Energy-Dispersive X-Ray Spectroscopy (EDX) was used to investigate the surface composition of the two studied material surfaces. The data were statistically analyzed using Independent T-Tests; the chosen significance level was α = 0.05. RESULTS: CF had significantly higher FT values compared to SO (p = 0.001). Also the FS results showed that CF had significantly higher values (90.11 MPa), followed by SO (22.15 MPa). The CS values showed the same order with significantly higher values for CF (231.79 MPa). While the FM and VH showed the reverse order with SO having significantly higher values than CF. pH measurements showed that CF evolved towards significantly higher pH values after 3 weeks in distilled water, while thermal properties showed more stability and higher resistance to degradation for CF compared to SO. The silver nitrate penetration results showed significantly better sealing ability for CF compared to the self-adhesive SO. Finally, EDX surface analysis results were consistent with the release profiles and confirmed the composition of the two tested materials. SIGNIFICANCE: Both materials, demonstrated enhanced Fluoride release ability, and hence good remineralisation potential in vitro that could prevent recurrent carious lesions in vivo. The composition based on acrylic polymerization showed better mechanical resistance to bending and fracture, and higher sealing ability than those based on acid base reaction.
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Fluoruros , Nitrato de Plata , Dureza , Materiales Dentales/química , Resinas Compuestas/química , Agua , Ensayo de Materiales , Propiedades de SuperficieRESUMEN
Gold-sulfur interaction has vital importance in nanotechnologies and material chemistry to design functional nanoparticles, self-assembled monolayers, or molecular complexes. In this paper, a mixture of only two basic precursors, such as the chloroauric acid (HAu(III)Cl4) and a thiol molecule (p-fluorothiophenol (p-HSPhF)), are used for the synthesis of gold(I)-thiolate coordination polymers. Under different conditions of synthesis and external stimuli, five different functional materials with different states of [Au(I)(p-SPhF)]n can be afforded. These gold-thiolate compounds are (i) red emissive, flexible, and crystalline fibers; (ii) composite materials made of these red emissive fibers and gold nanoparticles; (iii) amorphous phase; (iv) transparent glass; and (v) amorphous-to-crystalline phase-change material associated with an ON/OFF switch of luminescence. The different functionalities of these materials highlight the great versatility of the gold(I) thiolate coordination polymers with easy synthesis and diverse shaping that may have great potential as sustainable phosphors, smart textiles, sensors, and phase change memories.
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Herein, we report new insights into the nucleation and growth processes of chrysotile nanotubes by using batch and semi-continuous experiments. For the synthesis of this highly carcinogenic material, the influences of temperature (90, 200, and 300 °C), Si/Mg molar ratio, and reaction time were investigated. From the semi-continuous experiments (i.e., sampling of the reacting suspension over time) and solid-state characterization of the collected samples by XRPD, TGA, FTIR spectroscopy, and FESEM, three main reaction steps were identified for chrysotile nucleation and growth at 300 °C: 1)â formation of the proto-serpentine precursor within the first 2â h of the reaction, accompanied by the formation of brucite and residual silica gel; 2)â spontaneous nucleation and growth of chrysotile between about 3 and 8â h reaction time, through a progressive dissolution of the proto-serpentine, brucite, and residual silica gel; and 3)â Ostwald ripening growth of chrysotile from 8 to 30â h reaction time, as attested to by BET and FESEM measurements. Complementary results from batch experiments confirmed a significant influence of the reaction temperature on the kinetics of chrysotile formation. However, FESEM observations revealed some formation of chrysotile nanotubes at low temperatures (90 °C) after 14â days of reaction. Finally, doubling the Si/Mg molar ratio promoted the precipitation of pure smectite (stevensite-type) under the same P (8.2â MPa)/T (300 °C)/pH (13.5) conditions.
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Near room temperature hysteretic thermo-induced valence tautomerism was discovered in a layered 2D-coordination polymer of manganese(ii) with nitronyl nitroxide radicals separated by ClO4- anions (1). This opens a novel approach towards switchable materials with hysteresis and under ambient conditions with prospects for applications and for investigating solid-state intramolecular electron transfers. Herein, two new compounds with similar layered structures where the anions (X) are BF4- (2) or PF6- (3) are presented. Their magnetic behaviors also reveal hysteretic thermo-induced valence tautomeric conversions but in two steps and evidencing a strong effect of the anion. This occurs near room temperature (278-220 K) for 2 and higher for 3 (380-330 K). Their single crystal structures at different temperatures show that this involves two successive thermally-triggered electron transfers with switching between three redox tautomers formulated as {[MnII2-yMnIIIy(NITIm)3-y(NITRed)y]X}n, where y is temperature dependent. Upon cooling from the high-temperature redox-tautomer (y = 0) to the intermediate one (y = 1), half of the manganese(ii) centers are oxidized to manganese(iii) and 1/3 of the nitronyl nitroxide radicals (NITIm-) are reduced to the aminoxyl form (NITRed2-). On further cooling, the second half of the manganese(ii) centers are oxidized and another 1/3 of the radicals are reduced to reach the low-temperature redox-tautomer (y = 2). Upon reheating, reverse electron transfers occur. This is complementarily supported by X-ray powder measurements, differential scanning calorimetry, and electron paramagnetic resonance and Raman spectroscopies. These multi-stable compounds in which manganese ions exchange reversibly their electron with the nitronyl nitroxide radical are outstanding rare examples of two-step valence tautomerism in the solid state promoted by the polymeric structure.
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Obtaining transparent glasses made of functional coordination polymers (CPs) represents a tremendous opportunity for optical applications. In this context, the first transparent and red-emissive glasses of gold thiolate CPs have been obtained by simply applying mechanical pressure to amorphous powders of CPs. The three gold-based CP glasses are composed of either thiophenolate [Au(SPh)] n , phenylmethanethiolate [Au(SMePh)] n or phenylethanethiolate [Au(SEtPh)] n . The presence of a longer alkyl chain between the thiolate and the phenyl ring led to the formation of glass with higher transparency. The glass transitions, measured by thermomechanical analysis (TMA), occurred at lower temperature for CPs with longer alkyl chains. In addition, all three gold thiolate glasses exhibit red emission at 93 K and one of them, [Au(SMePh)] n , remains luminescent even at room temperature. An in-depth structural study of the amorphous gold thiolates by XRD, PDF and EXAFS analysis showed that they are formed of disordered doubly interpenetrated helical chains. These d10 metal-based compounds represent the first examples of transparent and luminescent CP glasses.
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Au25(SG)18 (SG - glutathione) clusters deposited on ZrO2 nanoparticles have been used as a catalyst for benzyl alcohol oxidation. Calcination was performed at different temperatures to study the ligand and particle size effect on the catalytic activity. In contrast to most gold nanoclusters which have to be completely defunctionalized for maximum catalytic activity, the partially defunctionalized Au25(SG)18@ZrO2 catalyst, thermally treated at 300 °C, exhibits full conversion of benzyl alcohol within 15 h under atmospheric pressure with 94% selectivity towards benzaldehyde.
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One thousand twenty-eight (1,028) patients with pain due to osteoarthritis (OA) of the knee were enrolled in this multicenter, randomized, double-blind, parallel study designed to assess the analgesic efficacy and safety of Tramadol Contramid OAD compared to placebo. An open-label phase was followed by a double-blind phase, in which a total of 646 patients were randomized to double-blind treatment with placebo or Tramadol Contramid OAD. Patients were titrated to their optimal dose (200mg or 300 mg), which was maintained for 12 weeks. An absolute mean reduction of 3.0+/-2.1 on a Pain Intensity Numerical Rating Scale (PI-NRS) was noted in the Tramadol Contramid OAD treatment group. The difference between active and placebo groups regarding this absolute mean reduction was statistically significant (P<0.001) throughout the study. The responder analysis demonstrated that a significantly greater percentage of patients in the active treatment arm achieved a reduction of >or=1 and >or=2 points on the PI-NRS score by the end of the study (P=0.035). A significantly greater percentage of respondents in the Tramadol Contramid OAD group indicated improvement on both the Patient and Physician Global Impressions of Change (P=0.0002). Both the 200mg and 300 mg doses contributed to the overall superiority of Tramadol Contramid OAD. The most frequent adverse events were consistent with the known side effects of tramadol and were generally mild to moderate in intensity. These results confirm that Tramadol Contramid OAD given once daily is an efficacious and safe treatment for pain due to OA.
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Analgésicos Opioides/uso terapéutico , Preparaciones de Acción Retardada/uso terapéutico , Osteoartritis de la Rodilla/complicaciones , Dolor/tratamiento farmacológico , Dolor/etiología , Tramadol/uso terapéutico , Anciano , Analgésicos Opioides/efectos adversos , Preparaciones de Acción Retardada/efectos adversos , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tramadol/efectos adversos , Resultado del TratamientoRESUMEN
This study gives relevant information on the variation of concentrations of certain volatile organic compounds (BTEX, alkanes, organochlorides and terpenes) emitted by open cells receiving municipal solid waste. These compounds represent a large fraction of the total trace components present in landfill gas. The VOC measurements were carried out in the atmosphere of an open landfill cell as a function of time and meteorological parameters, but also as a function of the activity of trucks unloading waste and compaction vehicles, in order to identify the factors that influence VOC emissions. Comparisons were performed systematically between the surface of the open cell and the corresponding mechanical activity. The measurements carried out during the course of the day highlighted the influence of air temperature and waste composition on VOC emissions while measurements of activity showed that the activity of fresh waste compaction vehicles is responsible for the highest VOC emissions. Such information is essential since most of the data in the literature relate to analyses of VOC traces in the biogas network and not in the air of the open cells as a function of different parameters (i.e. meteorological parameters, activity on the site). The highest VOC concentrations (in microg/m3) in the area of an open cell were obtained for: tetrachloroethylene (9810), toluene (8230), limonene (4550), m-xylene (3980) and trichloroethylene (3680). The results showed that the TWA values (the time-weighted average concentrations for up to an 8-h workday) established by INRS/France for the personnel in the station were complied with on the site studied.
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Compuestos Orgánicos/análisis , Compuestos Orgánicos/química , Eliminación de Residuos , Contaminantes del Suelo/química , Cromatografía de Gases y Espectrometría de Masas , Temperatura , Factores de Tiempo , VolatilizaciónRESUMEN
Boron- and nitrogen-based materials have shown to be attractive for solid-state chemical hydrogen storage owing to gravimetric hydrogen densities higher than 10 wt% H. Herein, we report a new derivative of hydrazine borane N2H4BH3, namely lithium hydrazinidoborane ammoniate LiN2H3BH3·0.25NH3. It is easily obtained in ambient conditions by ball-milling N2H4BH3 and lithium amide LiNH2 taken in equimolar amounts. Both compounds react without loss of any H atoms. The molecular and crystallographic structures of our new compound have been confirmed by NMR/FTIR spectroscopy and powder X-ray diffraction. The complexation of the entity LiN2H3BH3 by some NH3 has been also established by thermogravimetric and calorimetric analyses. In our conditions, LiN2H3BH3·0.25NH3 has been shown to be able to release H2 at temperatures lower than the parent N2H4BH3 or the counterpart LiN2H3BH3. It also liberates non-negligible amounts of NH3 at temperatures lower than 100 °C. This is actually quite detrimental for chemical H storage, but alternatively LiN2H3BH3·0.25NH3 might be seen as a potential NH3 carrier.
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In the field of solid-state chemical hydrogen storage, ammonia borane NH3BH3 has been widely studied while hydrazine borane N2H4BH3 can be considered as a "novel" material. In the present work, we investigated the behaviour of these boranes when mixed together in a mole ratio of 1:1. Hydrazine borane and ammonia borane destabilize each other. Though stable at 20-25 °C, the mixture melts at â¼ 30 °C and then undergoes significant decomposition, with desorption of hydrogen H2 and hydrazine N2H4 from 67 °C. This is explained by the fact that the presence of hydrazine borane disrupts the H(δ+)⯠H(δ-) network of ammonia borane, and vice versa; the mixture is then much less stable than the pristine boranes. The mixture can nevertheless be stabilized (by heat- or vacuum-treatment and thus extraction of evolving hydrogen and hydrazine), making the as-obtained solid a potential chemical hydrogen storage material. Over the range 25-300 °C, it is able to release ca. 11.4 wt% of almost pure H2. Furthermore forms boron nitride as the solid residue, at temperatures as low as 300 °C.
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Compuestos de Boro/química , Rastreo Diferencial de Calorimetría , Cromatografía de Gases y Espectrometría de Masas , Hidrógeno/química , Espectroscopía de Resonancia Magnética , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Termogravimetría , Difracción de Rayos XRESUMEN
Herein, we present the successful synthesis and full characterization (by (11) B magic-angle-spinning nuclear magnetic resonance spectroscopy, infrared spectroscopy, powder X-ray diffraction) of sodium hydrazinidoborane (NaN2 H3 BH3 , with a hydrogen content of 8.85 wt %), a new material for chemical hydrogen storage. Using lab-prepared pure hydrazine borane (N2 H4 BH3 ) and commercial sodium hydride as precursors, sodium hydrazinidoborane was synthesized by ball-milling at low temperature (-30 °C) under an argon atmosphere. Its thermal stability was assessed by thermogravimetric analysis and differential scanning calorimetry. It was found that under heating sodium hydrazinidoborane starts to liberate hydrogen below 60 °C. Within the range of 60-150 °C, the overall mass loss is as high as 7.6 wt %. Relative to the parent N2 H4 BH3 , sodium hydrazinidoborane shows improved dehydrogenation properties, further confirmed by dehydrogenation experiments under prolonged heating at constant temperatures of 80, 90, 95, 100, and 110 °C. Hence, sodium hydrazinidoborane appears to be more suitable for chemical hydrogen storage than N2 H4 BH3 .
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Boranos/química , Hidrazinas/química , Hidrógeno/química , Rastreo Diferencial de Calorimetría , Calor , Espectroscopía de Resonancia Magnética , Compuestos de Sodio/química , Espectrofotometría Infrarroja , TermogravimetríaRESUMEN
New Au(25) nanoclusters stabilized by heterotopic 4-aminothiophenolate ligands (HSPhNH(2)) have been isolated with a yield of ~70%. The nanoclusters formula determined by ESI-MS is Au(25)(SPhNH(2))(17), with the 18(th) position occupied by an amine or DMF molecules to close their electronic shell.
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UNLABELLED: The study aims to assess and compare the efficiency of two different kinetic programmes, in order to improve the treatment of patients with ankylosing spondylitis (AS). MATERIAL AND METHOD: Our study included two samples (control and cases) of 30 patients admitted for AS and unilateral coxitis in the Clinic of Rheumatology and Medical Rehabilitation Iasi, between 2008-2009. Certain paramentres such as: age, body mass index, disease evolution, Schober test, index-earth test, inspir-expir index, BASDAI activity index, BASFI functional index, Health Assessment Questionaire (HAQ), pain, morning ankylosing inflammatory tests, and general state of health were assessed at every patient. RESULTS: No variation with statistical significance were registered between the two samples. The Pilates method used in the rehabilitation treatment of patients with AS could have a favourable effect on indices regarding mobility, as well as patients' perception about their disease.
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Terapia por Ejercicio , Osteoartritis de la Cadera/rehabilitación , Espondilitis Anquilosante/rehabilitación , Adulto , Estudios de Casos y Controles , Progresión de la Enfermedad , Terapia por Ejercicio/métodos , Humanos , Osteoartritis de la Cadera/etiología , Dolor/etiología , Calidad de Vida , Rango del Movimiento Articular , Medición de Riesgo , Rumanía , Índice de Severidad de la Enfermedad , Espondilitis Anquilosante/complicaciones , Encuestas y CuestionariosRESUMEN
Single- and multibranched centrosymmetric derivatives incorporating B12 clusters [B12H11-N(H)=C(H)-C6H4-C6H4-C(H)=(H)N-B12H11]2- (3) and [1,3,5-(4-(B12H11-N(H)=C(H))-C6H4)-C6H3]3- (5) have been synthesized. Both derivatives were characterized by multinuclear NMR and ESI-MS analyses. To the best of our knowledge, compound 5 is the first example of a multicage derivative bearing three B12 units. Compounds 3 and 5 are only slightly yellowish colored. The UV-vis absorption curves of 3 and 5 show intense absorption bands at 360 and 314 nm, respectively. This result permits us to confirm the strong donor effect of the B12 cluster. The hypsochrome effect observed for compound 5 compared to that of compound 3 confirms the interest in multibranched derivatives for the preparation of two-photon absorption materials active in the visible range.
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The authors present a rare case of bilateral temporomandibular joint ankylosis secondary to polyarticular juvenile psoriatic arthritis in a 24 year-old man. The patient first presented with arthritis of his right elbow joint at the age of 9, followed by involvement of the distal inter-phalangeal joints of his right foot and both sacroiliac joints. Serum rheumatoid factor was not detected. At the age of 16 he developed psoriatic lesions affecting his nails and skin. By the age of 20, clinical and radiological evidence of arthritis was detected in his temporomandibular joint (TMJ). Subsequently, the patient developed bilateral TMJ ankylosis over a period of 4 years. The patient was managed by bilateral resection of the ankylosis bone blocks, mobilization of the mandible and interposition of Dacron material between the two neo-articular surfaces. 10 months postoperatively the patient maintained an inter-incisal distance of 3 cm. Postoperative mechano-therapy was hindered by the limited use of the patients' hands.