Copper Single Atoms Chelated on Ligand-Modified Carbon for Ullmann-Type C-O Coupling

Invited for this month's cover is the group of Gianvito Vilé at the Politecnico di Milano. The ChemSusChem cover image depicts in an artistic manner the concept of ligand entrapping of isolated metals to design single-atom catalysts. The Research Article itself is available at 10.1002/cssc.202301529.

Copper Single Atoms Chelated on Ligand-Modified Carbon for Ullmann-type C-O Coupling

Cross-coupling reactions are of great importance in chemistry due to their ability to facilitate the construction of complex organic molecules. Among these reactions, the Ullmann-type C-O coupling between phenols and aryl halides is particularly noteworthy and useful for preparing diarylethers. However, this reaction typically relies on homogeneous catalysts that rapidly deactivate under harsh reaction conditions. In this study, we introduce a novel heterogeneous catalyst for the Ullmann-type C-O coupling reaction, comprised of isolated Cu atoms chelated to a tetraethylenepentamine-pyrrole ligand that is immobilized on graphite nanoplatelets. The catalytic study reveals the recyclability of the material, and demonstrates the crucial role of the pyrrole linker in stabilizing the Cu sites. The work expands the potential of single-atom catalyst nanoarchitectures and underscores the significance of ligands in stabilizing metals in cationic forms, providing a novel, tailored catalyst for cross-coupling chemistries.

Pyrrole Compounds from the Two-Step One-Pot Conversion of 2,5-Dimethylfuran for Elastomer Composites with Low Dissipation of Energy

A one-pot, two-step process was developed for the preparation of pyrrole compounds from 2,5-dimethylfuran. The first step was the acid-catalyzed ring-opening reaction of 2,5-dimethylfuran (DF), leading to the formation of 2,5-hexanedione (HD). A stoichiometric amount of water and a sub-stoichiometric amount of sulfuric acid were used by heating at 50 °C for 24 h. Chemically pure HD was isolated, with a quantitative yield (up to 95%), as revealed by 1H-NMR, 13C-NMR, and GC-MS analyses. In the second step, HD was used as the starting material for the synthesis of pyrrole compounds via the Paal-Knorr reaction. Various primary amines were used in stoichiometric amounts. 1H-NMR, 13C-NMR, ESI-Mass, and GC-Mass analyses confirmed that pyrrole compounds were prepared with very good/excellent yields (80-95%), with water as the only co-product. A further purification step was not necessary. The process was characterized by a very high carbon efficiency, up to 80%, and an E-factor down to 0.128, whereas the typical E-factor for fine chemicals is between 5 and 50. Water, a co-product of the second step, can trigger the first step and therefore make the whole process circular. Thus, this synthetic pathway appears to be in line with the requirements of a sustainable chemical process. A pyrrole compound bearing an SH group (SHP) was used for the functionalization of a furnace carbon black (CB). The functionalized CB (CB/SHP) was utilized in place of silica, resulting in a 15% mass reduction of reinforcing filler, in an elastomeric composite based on poly(styrene-co-butadiene) from solution anionic polymerization and poly(1,4-cis-isoprene) from Hevea Brasiliensis. Compared to the silica-based composite, a reduction in the Payne effect of about 25% and an increase in the dynamic rigidity (E' at 70 °C) of about 25% were obtained with CB/SHP.

Hexagonal Boron Nitride as Filler for Silica-Based Elastomer Nanocomposites

Two-dimensional hexagonal boron nitride (hBN) has attracted tremendous attention over the last few years, thanks to its stable structure and its outstanding properties, such as mechanical strength, thermal conductivity, electrical insulation, and lubricant behavior. This work demonstrates that hBN can also improve the rheological and mechanical properties of elastomer composites when used to partially replace silica. In this work, commercially available pristine hBN (hBN-p) was exfoliated and ball-mill treated in air for different durations (2.5, 5, and 10 h milling). Functionalization occurred with the -NH and -OH groups (hBN-OH). The functional groups were detected using Fourier-Transform Infrared pectroscopy (FT-IR) and were estimated to be up to about 7% through thermogravimetric analysis. The presence of an increased amount of oxygen in hBN-OH was confirmed using Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy. (SEM-EDS). The number of stacked layers, estimated using WAXD analysis, decreased to 8-9 in hBN-OH (10 h milling) from about 130 in hBN-p. High-resolution transmission electron microscopy (HR-TEM) and SEM-EDS revealed the increase in disorder in hBN-OH. hBN-p and hBN-OH were used to partially replace silica by 15% and 30%, respectively, by volume, in elastomer composites based on poly(styrene-co-butadiene) from solution anionic polymerization (S-SBR) and poly(1,4-cis-isoprene) from Hevea Brasiliensis (natural rubber, NR) as the elastomers (volume (mm3) of composites released by the instrument). The use of both hBNs in substitution of 30% of silica led to a lower Payne effect, a higher dynamic rigidity, and an increase in E' of up to about 15% at 70 °C, with similar/lower hysteresis. Indeed, the composites with hBN-OH revealed a better balance of tan delta (higher at low temperatures and lower at high temperatures) and better ultimate properties. The functional groups reasonably promote the interaction of hBN with silica and with the silica's coupling agent, sulfur-based silane, and thus promoted the interaction with the elastomer chains. The volume of the composite, measured using a high-pressure capillary viscometer, increased by about 500% and 400% after one week of storage in the presence of hBN-p and hBN-OH. Hence, both hBNs improved the processability and the shelf life of the composites. Composites obtained using hBN-OH had even filler dispersion without the detachments of the filler from the elastomer matrix, as shown through TEM micrographs. These results pave the way for substantial improvements in the important properties of silica-based composites for tire compounds, used to reduce rolling resistance and thus the improve environmental impacts.

Adsorption Affinities of Small Volatile Organic Molecules on Graphene Surfaces for Novel Nanofiller Design: A DFT Study

The adsorption of organic molecules on graphene surfaces is a crucial process in many different research areas. Nano-sized carbon allotropes, such as graphene and carbon nanotubes, have shown promise as fillers due to their exceptional properties, including their large surface area, thermal and electrical conductivity, and potential for weight reduction. Surface modification methods, such as the "pyrrole methodology", have been explored to tailor the properties of carbon allotropes. In this theoretical work, an ab initio study based on Density Functional Theory is performed to investigate the adsorption process of small volatile organic molecules (such as pyrrole derivatives) on graphene surface. The effects of substituents, and different molecular species are examined to determine the influence of the aromatic ring or the substituent of pyrrole's aromatic ring on the adsorption energy. The number of atoms and presence of π electrons significantly influence the corresponding adsorption energy. Interestingly, pyrroles and cyclopentadienes are 10 kJ mol-1 more stable than the corresponding unsaturated ones. Pyrrole oxidized derivatives display more favorable supramolecular interactions with graphene surface. Intermolecular interactions affect the first step of the adsorption process and are important to better understand possible surface modifications for carbon allotropes and to design novel nanofillers in polymer composites.

Bio-Based Pyrrole Compounds Containing Sulfur Atoms as Coupling Agents of Carbon Black with Unsaturated Elastomers

In this work, the hysteresis of elastomer composites suitable for tire compounds was reduced by using CB functionalized with pyrrole compounds containing sulfur-based functional groups reactive with the elastomer chains. CB was functionalized with bio-based pyrrole compounds: 2-(2,5-dimethyl-1H-pyrrol-1-yl)ethane-1-thiol (SHP) and 1,2-bis(2-(2,5-dimethyl-1H-pyr-rol-1-yl)ethyl)disulfide (SSP), bearing an -SH and an -SS- functional group, respectively. SHP and SSP were synthesized via a one-pot two-step synthesis, with yields higher than 70%, starting from biosourced chemicals as follows: 2,5-hexanedione from 2,5-dimethylfuran, cysteine and cysteamine. The functionalization of CB was carried out by mixing the CB with PyC and heating, with quantitative yields ranging from 92 to 97%. Thus, the whole functionalization process was characterized by a high carbon efficiency. The formation of the covalent bond between SHP, SSP and CB, in line with the prior art of such a functionalization technology, was proven by means of extraction and TGA analyses. The reactivity of the sulfur-based functional groups with unsaturated polymer chains was demonstrated by using squalene as the model compound. Poly(styrene-co-butadiene) from solution anionic polymerization and poly(1,4-cis-isoprene) from Hevea Brasiliensis were the elastomers employed for the preparation of the composites, which were crosslinked with a sulfur-based system. Pristine CB was partially replaced with CB/SHP (33%) and CB/SSP (33% and 66%). The PyC resulted in better curing efficiency, an increase in the dynamic rigidity of approximately 20% and a reduction in the hysteresis of approximately 10% at 70 °C, as well as similar/better ultimate tensile properties. The best results were achieved with a 66% replacement of CB with CB/SSP. This new family of reactive carbon blacks paves the way for a new generation of 'green tires', reinforced by a CB reactive with the polymer chains, which provides high mechanical properties and low rolling resistance. Such a reactive CB eliminates the use of silica, and thus the ethanol emission resulting from the condensation of silane is used as a coupling agent. In addition, CB-based tires are characterized by a higher mileage, at a moment in which the reduction in tire wear has become a primary concern.

Polyhydroxylated Nanosized Graphite as Multifunctional Building Block for Polyurethanes

Polyurethane nanocomposites were prepared with a nanosized high surface area graphite (HSAG) functionalized on its edges with hydroxyl groups as a building block. Edge functionalization of HSAG was obtained through reaction with KOH. The addition of OH groups was demonstrated by means of infrared (FTIR) and thermogravimetric analysis (TGA), and the Boehm titration allowed estimation of a level of about 5.0 mmol_OH/g_HSAG. Results from wide-angle X-ray diffraction (WAXD) and Raman spectroscopy suggested that functionalization of the graphene layers occurred on the edges. The evaluation of the Hansen solubility parameters of G-OH revealed a substantial increase of δ_P and δ_H parameters with respect to HSAG. In line with these findings, homogeneous and stable dispersions of G-OH in a polyol were obtained. PU were prepared by mixing a dispersion of G-OH in cis-1,4-butenediol with hexamethylene diisocyanate. A model reaction between catechol, 1,4-butanediol, and hexamethylene diisocyanate demonstrated the reactivity of hydroxylated aromatic rings with isocyanate groups. PU-based G-OH, characterized with WAXD and differential scanning calorimetry (DSC), revealed lower T_g, higher T_c, T_m, and crystallinity than PU without G-OH. These results could be due to the higher flexibility of the polymer chains, likely a consequence of the dilution of the urethane bonds by the carbon substrate. Hence, G-OH allowed the preparation of PU with a larger temperature range between T_g and T_m, with potential positive impact on material applications. The model reaction between butylisocyanate and 1-butanol revealed that HSAG and G-OH promote efficient formation of the urethane bond, even in the absence of a catalyst. The effect of high surface area carbon on the nucleophilic oxygen attack to the isocyanate group can be hypothesized. The results here reported lead us to comment that a reactive nanosized sp² carbon allotrope, such as G-OH, can be used as a multifunctional building block of PU. Indeed, G-OH is a comonomer of PU, a promoter of the polymerization reaction, and can definitely act as reinforcing filler by tuning its amount in the final nanocomposite leading to highly versatile materials. The larger temperature range between T_g and T_m, together with the presence of G-OH acting as a reinforcing agent, could allow the production of piezoresistive sensing, shape-memory PU with good mechanical features.

Bionanocomposites based on a covalent network of chitosan and edge functionalized graphene layers

In this study, carbon papers and aerogels were prepared from chitosan and graphene layers with aldehydic edge functional groups (G-CHO) able to form chemical bonds with chitosan and thus to form a crosslinked network. A high surface area graphite was edge functionalized with hydroxyl groups (G-OH) through the reaction with KOH. G-CHO, with 4.5 mmol/g of functional group, was prepared from G-OH by means of the Reimer-Tieman reaction. Characterization of the graphitic materials was performed with elemental analysis, titration, X-ray analysis, Raman spectroscopy and by estimating their Hansen solubility parameters. CS and G-CHO were mixed with mortar and pestle and carbon papers and aerogels were obtained from a stable acidic water suspension through casting and liophilization, respectively. Free standing and foldable carbon papers and monolithic aerogels based on a continuous covalent network between G-CHO and CS were prepared. G-CHO, which had about 22 stacked layers, was extensively exfoliated in the carbon paper, as confirmed by the absence of the 002 reflection of the graphitic crystallites in the XRD pattern. Carbon paper was found to be resistant to solvents and to be stable for pH ⩾ 7. Composites revealed electrical conductivity. The covalent network between the graphene layers and CS, suggested by the IR findings, accounts for these results. This work demonstrates the effectiveness of a continuous covalent network between chitosan and graphene layers edge functionalized with tailor made functional groups for the preparation of carbon papers and aerogels and paves the way for the scale up of such a type of composites.

A Graphene-Based Supramolecular Nanoreactor for the Fast Synthesis of Imines in Water

The confinement of organic synthesis within waterborne nanoreactors is regarded with increasing attention to improve its yield and reduce the environmental impact. However, many catalysts, such as graphene, are barely dispersible in aqueous media and many chemical reactions cannot be performed in the presence of water due to thermodynamic limitations. Therefore, there is an urgent need to develop novel strategies to carry out these processes in more sustainable conditions. To pursue this goal, in this work, a waterborne supramolecular nanoreactor is developed. The system comprises a polymeric micelle obtained from the self-assembly of pyrrole-based amphiphilic block copolymers. The active catalytic component is represented by few graphene layers, functionalized with pyrrole to enhance their interaction with the micelle core and hence their nanoencapsulation. Using this nanoreactor, it is possible to synthesize imines starting from primary amines and aldehydes or ketones with high yield and in short time (Y = 90% after 5 min) at room temperature. Moreover, an efficient strategy to recycle the reactor is proposed, thus increasing the potential of this technology.

Tuning the Solubility Parameters of Carbon Nanotubes by Means of Their Adducts with Janus Pyrrole Compounds

The solubility parameters of multiwalled carbon nanotubes (CNTs) was tuned via their chemical modification with pyrrole compounds (PyCs), by means of a simple and sustainable methodology. PyCs were synthesized with high atom efficiency through the Paal–Knorr reaction of primary amines with 2,5-hexanedione, in the absence of solvents and catalysts. Methylamine, 1-dodecylamine, 2-amino-1,3-propanediol, and 3-(triethoxysilyl)propan-1-amine were selected. PyCs are characterized by two moieties, the pyrrole ring and the substituent of the nitrogen atom, and can be considered as Janus molecules. The functionalization of CNTs occurred with a high yield by simply heating CNTs and PyC. The whole reaction pathway did not produce any waste and was characterized by a carbon efficiency up to almost 100%. Thanks to the variety of PyC chemical structures, the CNT solubility parameter was modified in a pretty broad range of values, in the expected direction. Stable CNT dispersions were prepared in different solvents. From the aqueous dispersion, coating layers were prepared with high electrical conductivity, larger with respect to a top commercial product. The “pyrrole methodology” reported here is based on one reaction and allows almost infinite variations of the CNT solubility parameter, thus promoting their compatibility with target matrices and allowing the preparation of nanocomposite materials with improved properties. This work thus paves the way for a highly efficient exploitation of CNTs.

Time-resolved thermally induced aberrations in a flash-lamp pumped Nd:Glass disk amplifier using a 2 × 2 position sensitive detector array

A novel technique of measuring the prompt, thermally induced wave-front aberrations in a large aperture flash-lamp pumped Nd³⁺ glass disk amplifier is presented. Implementing a 2 × 2 lens array and a 2 × 2 position sensitive detector array as a diagnostic system, the wave-front profile was successfully reconstructed for the first five Zernike terms for a temporal window of 8.5 ms.

Domino Reaction for the Sustainable Functionalization of Few-Layer Graphene

The mechanism for the functionalization of graphene layers with pyrrole compounds was investigated. Liquid 1,2,5-trimethylpyrrole (TMP) was heated in air in the presence of a high surface area nanosized graphite (HSAG), at temperatures between 80 °C and 180 °C. After the thermal treatments solid and liquid samples, separated by centrifugation, were analysed by means of Raman, Fourier Transform Infrared (FT-IR) spectroscopy, X-Rays Photoelectron Spectroscopy (XPS) and ¹H-Nuclear Magnetic Resonance (¹H NMR) spectroscopy and High Resolution Transmission Electron Microscopy (HRTEM). FT-IR spectra were interpreted with the support of Density Functional Theory (DFT) quantum chemical modelling. Raman findings suggested that the bulk structure of HSAG remained substantially unaltered, without intercalation products. FT-IR and XPS spectra showed the presence of oxidized TMP derivatives on the solid adducts, in a much larger amount than in the liquid. For thermal treatments at T ≥ 150 °C, IR spectral features revealed not only the presence of oxidized products but also the reaction of intra-annular double bond of TMP with HSAG. XPS spectroscopy showed the increase of the ratio between C(sp²)N bonds involved in the aromatic system and C(sp³)N bonds, resulting from reaction of the pyrrole moiety, observed while increasing the temperature from 130 °C to 180 °C. All these findings, supported by modeling, led to hypothesize a cascade reaction involving a carbocatalyzed oxidation of the pyrrole compound followed by Diels-Alder cycloaddition. Graphene layers play a twofold role: at the early stages of the reaction, they behave as a catalyst for the oxidation of TMP and then they become the substrate for the cycloaddition reaction. Such sustainable functionalization, which does not produce by-products, allows us to use the pyrrole compounds for decorating sp² carbon allotropes without altering their bulk structure and smooths the path for their wider application.

Air pollution deposition on a roadside vegetation barrier in a Mediterranean environment: Combined effect of evergreen shrub species and planting density

Leaf deposition of PM_10-100, PM_2.5-10, PM_0.2-2.5 and of 21 elements was investigated in a roadside vegetation barrier formed by i) two evergreen shrub species (Photinia × fraseri, Viburnum lucidum), with ii) two planting densities (0.5, 1.0 plant m^-2), at iii) three distances from the road (2.0, 5.5, 9.0 m), at iv) two heights from the ground (1.5, 3.0 m), and on v) three dates (Aug, Sep, Oct). The presence of black and brown on-leaf PM_10-100 and their element composition were detected by microscopy and image analysis. Pollutant deposition was also measured using passive samplers at five distances from the road (2.0, 5.5, 9.0, 12.5, 19.5 m) in the area of the barrier and in an adjacent lawn area. V. lucidum had more PM_2.5-10 and PM_0.2-2.5 on leaves than P. × fraseri, while most elements were higher in P. × fraseri. Most pollutants decreased at increasing distances from the road and were higher at 1.5 m from the ground compared to 3.0 m. Higher planting density in P. × fraseri enhanced the deposition of PM_10-100 and PM_2.5-10, while in V. lucidum, the planting density did not affect the depositions. Black PM_10-100 decreased a long distance from the road and was entirely composed of carbon and oxygen, which was thus identified as black carbon from fuel combustion. The vegetation barrier had a higher deposition of most PM fractions at 5.5-12.5 m, while in the lawn area, depositions did not change. At 19.5 m, the PM_10-100 was 32% lower behind the barrier than in the lawn area. In conclusion, the vegetation barrier changed the deposition dynamics of pollutants compared to the lawn area. These results strengthen the role of vegetation barriers and shrub species against air pollution and may offer interesting insights for the use of new road green infrastructures to improve air quality.

Single-shot frequency-resolved optical gating for retrieving the pulse shape of high energy picosecond pulses

Accurate characterization of laser pulses used in experiments is a crucial step to the analysis of their results. In this paper, a novel single-shot frequency-resolved optical gating (FROG) device is described, one that incorporates a dispersive element which allows it to fully characterize pulses up to 25 ps in duration with a 65 fs per pixel temporal resolution. A newly developed phase retrieval routine based on memetic algorithms is implemented and shown to circumvent the stagnation problem that often occurs with traditional FROG analysis programs when they encounter a local minimum.

SERINOL DERIVATIVES FOR THE SUSTAINABLE VULCANIZATION OF DIENE ELASTOMERS

2-amino-1,3-propandiol (serinol) was used as the starting building block of synthetic pathways that led to the preparation of innovative chemicals suitable as ingredients for rubber compounds. Serinol based reactions were performed in the frame of a sustainable process, in the absence of any solvent and catalyst, with aldehydes and ketones, such as acetone, cinnamaldehyde and camphor. The synthesis of either imines or oxazolidines was obtained with high selectivity. Serinol, imine and oxazolidine derivatives of serinol were used as accelerator for the vulcanization of diene rubbers. They were proved to be efficient secondary accelerators in silica based compounds based on poly(styrene-co-butadiene) in place of diphenyl guanidine. The kinetics of vulcanization was investigated for natural rubber based compounds in the absence of any filler. With respect to serinol, the imine derivatives were able to enhance the induction time of vulcanization and to afford a similar vulcanization rate.

Facile and sustainable functionalization of graphene layers with pyrrole compounds

A facile and sustainable functionalization of graphene layers was performed with pyrrole compounds (PyC) prepared through the Paal–Knorr reaction of a primary amine with 2,5-hexanedione. A good number of primary amines were used: hexanamine, dodecanamine, octadecanamine, 2-aminoacetic acid, 2-amino-1,3-propanediol, 3-(triethoxysilyl)propan-1-amine. The reactions were characterized by good yield, up to 96%, and indeed satisfactory atom efficiency, up to 80%. The functionalization of graphene layers was obtained by mixing PyC with a high surface area graphite and heating at a temperature range from 130°C to 150°C for 3 h. The yield of functionalization reaction was larger than 60% and also up to about 90% for the pyrrole compounds from dodecanamine and 2-amino-1,3-propanediol, respectively. The cycloaddition reaction between the graphene layers and the pyrrole compound, oxidized in two position, is proposed as working hypothesis to account for such efficient functionalization. Raman spectroscopy revealed that the structure of the graphitic substrate remained substantially unaltered, after the reaction. Stable dispersions of HSAG adducts with different PyC were prepared in solvents with different solubility parameters and HRTEM analysis showed the presence of aggregates of only few layers of graphene. Qualitative results of dispersion tests were used to calculate the Hansen sphere for the HSAG adduct with the pyrrole compound based on dodecanamine so to provide a first estimate of its Hansen solubility parameters. This work paves the way for the facile and sustainable modification of the solubility parameters of graphene layers and for the predictive assessment of their compatibility with different environments.

FACILE FUNCTIONALIZATION OF sp2 CARBON ALLOTROPES WITH A BIOBASED JANUS MOLECULE

A simple, versatile, sustainable, not expensive method for the functionalization of sp2 carbon allotropes, both nano-sized and nano-structured, without altering their bulk crystalline organization, is presented. Carbon materials available at the commercial scale were used: furnace carbon black (CB), nano-sized graphite with high surface area, and multiwalled carbon nanotubes. A bio-sourced molecule, 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole), was used for the functionalization. Serinol pyrrole (SP) was obtained from serinol through a reaction with atomic efficiency of about 82%, performed in the absence of solvents or catalysts. Synthesis of serinol pyrrole was performed as well on carbon allotropes as the solid support. Adducts of serinol pyrrole with a carbon allotrope were prepared with the help of either thermal or mechanical energy. Functionalization yield was in all cases larger than 90%. With such adducts, stable dispersions in water and in NR latex were prepared. A few layers of graphene were isolated from the water dispersions, and NR-based composites precipitated from the latex revealed very even distribution of fine graphitic particles. Composites were prepared, based on NR, IR, and BR as the rubbers and CB and silica as the fillers, with different amounts of CB–SP adduct, and were cross-linked with a sulfur-based system without observing appreciable effect of functionalization on vulcanization kinetics. The CB–SP adduct led to appreciable reduction of the Payne effect.

Polyhydroxylated few layer graphene for the preparation of flexible conductive carbon paper

Electrically conductive flexible carbon papers were prepared, based on hydroxyl functionalized few layer graphene (G-OH).

Biobased Janus molecule for the facile preparation of water solutions of few layer graphene sheets

A biobased Janus molecule was used to prepare water solutions of nano-stacks made by few layer graphene.

RECENT ADVANCEMENTS IN RUBBER NANOCOMPOSITES

Nanocomposites were prepared via melt blending, based on organically modified clays (OC), carbon nanotubes (CNT), and graphitic nanofillers made by a few layers of graphene (nanoG). In particular, nanocomposites based on a hybrid filler system, with a nanostructured filler such as carbon black (CB), are examined. It is shown that low crystalline order in the interlayer space of a layered nanofiller (such as OC and nanoG) leads to easier delamination. Nanofillers give rise to filler networking at low concentration, particularly in the presence of CB. Hybrid filler systems lead to nanocomposites' having initial moduli that are much higher than those calculated through the sum of the initial modulus of composites containing either only CB or only the nanofiller. Nanofillers enhance the matrix modulus by a multiplication factor that depends only on the nanofiller type and content, regardless of whether the matrix is a neat or a CB-filled polymer. Furthermore, the filler–polymer interfacial area is shown to be a parameter able to correlate the mechanical behavior of both nano-CNT and nanostructured (CB) fillers. By plotting values of the composite initial modulus versus the filler–polymer interfacial area, points due to CB, CNT, and the hybrid CB-CNT system lie on the same curve.

Avoidance of nonsteroidal anti-inflammatory drugs after negative provocation tests in urticaria/angioedema reactions: Real-world experience

Drug provocation tests (DPTs) are the gold standard in diagnosing nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity; however, only few data about follow-up of patients with negative DPTs are actually available. The aim of this study was to assess patients' behavior in taking NSAIDs again and to evaluate NSAID tolerability after negative allergological workup. This is a follow-up study involving patients evaluated for history of cutaneous reactions (urticaria and or angioedema) after NSAID intake and with negative DPTs with the suspected NSAID. Patients were asked during a phone interview about the intake of NSAIDs, tolerance, or reasons of avoidance. The negative predictive value (NPV) of NSAIDs DPTs was calculated. One hundred eleven of 142 patients were successfully contacted; 46/111 (41.44%) took the same NSAID previously tested with two adverse reactions reported (4.34%). Fifty-three of 111 (47.74%) patients did not take the same NSAID, but 34 of them took at least another strong cyclooxygenase (COX) 1 inhibitor, with 1 adverse reaction (2.94%) and 19 of them took only weak COX-1 inhibitors. Twelve of 111 patients (10.8%) did not take any NSAID. Reasons for drug avoidance were mainly fear of reactions (70.8%) and no need (29.2%). NPV, overall, was 96.97% (95% confidence interval, 91-99%). Although NSAID hypersensitivity diagnosis was ruled out by oral provocation test, the majority of patients with a history of urticaria/angioedema avoided the intake of the tested NSAIDs for fear of new reactions, particularly when strong COX-1 inhibitor NSAIDs were involved. The high NPV value of DPT resulting from this study should reassure NSAID intake.

FILLER NETWORKING OF A NANOGRAPHITE WITH A HIGH SHAPE ANISOTROPY AND SYNERGISM WITH CARBON BLACK IN POLY(1,4-CIS-ISOPRENE)–BASED NANOCOMPOSITES

A nanoGraphite (nanoG) having a high surface area and a high shape anisotropy, defined as the ratio between the crystallite dimensions in a direction orthogonal and parallel to structural layers, was used to prepare nanocomposites based on poly(1,4-cis-isoprene) (IR), in the neat polymer matrix and in the presence of carbon black (CB). Tensile and dynamic-mechanical measurements showed that nanoG forms a filler network at a relatively low concentration in neat IR and a hybrid filler network at a lower nanoG concentration in the presence of CB. A synergistic effect between the two carbon allotropes was found: composites containing both fillers present initial modulus values much higher than those calculated through the simple addition of the initial moduli of the composites containing only CB or nanoG.

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

Supercritical carbon dioxide (scCO2) treatments of a montmorillonite (MMT) intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT) led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS), have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

Incidence of food anaphylaxis in Piemonte region (Italy): data from registry of Center for Severe Allergic Reactions

There are wide differences in estimated incidence and prevalence of anaphylaxis because of the absence, until recently, of a universal consensus on the definition of anaphylaxis and the different source of collected data. We aimed to estimate the incidence of food anaphylaxis based on the database of Piemonte Region (Italy) Reference Center for Severe Allergic Reactions. All cases of severe food allergic reactions reported in 2010 were studied. Clinical data associated to the reports were evaluated according to National Institute of Allergy and Infectious Disease and Food Allergy and Anaphylaxis Network diagnostic criteria of anaphylaxis. 75 % of the 778 cases were classified as food anaphylaxis (incidence of 13/100,000 person-years, ranging from 9.9 in adults to 29/100,000 person-years in children). Nuts were the most frequent foods causing anaphylaxis. Milk and eggs were responsible for anaphylaxis more often in children, while peach, vegetables and crustaceans were in adults. Cardiovascular symptoms were more frequent in adults. Gastrointestinal involvement was more frequent in children. A high prevalence of respiratory allergic comorbidities was observed. Food is an important cause of anaphylaxis, particularly in subjects with respiratory allergic comorbidities. Children and adults differ in triggers and clinical presentation of anaphylaxis.

Perioperative anaphylactic risk score for risk-oriented premedication

Basing on the current knowledge, this paper is aimed to review the core characteristics of the most relevant therapeutic agents (steroids and antihistamines), administered to prevent perioperative anaphylaxis. Moreover, the Authors propose the validation of a Global Anaphylactic Risk Score, built up by recording the individual scores related to the most relevant anaphylaxis parameters (i.e. medical history, symptoms and medication for asthma, rhinitis and urticaria etc) and by adding them on all together; the score could be used in the preoperative phase to evaluate the global anaphylactic risk and to prescribe risk-oriented premedication protocols.

A case of acute generalized exanthematous pustulosis due to amoxicillin-clavulanate with multiple positivity to beta-lactam patch testing

We present a case of acute generalized exanthematous pustolosis (AGEP) induced by amoxicillin-clavulanate. Clinical diagnosis was confirmed by symptoms presentation and  histological features (Euroscar score point compatible with definite diagnosis). Patch testing performer six months later confirmed sensitization to the culprit drug and showed positivity also to other beta-lactam antibiotics (penicillin G and cephalexin). We believe that a T cell delayed response to betalactams common ring could be involved.

Cutaneous reactions to heparin therapy: when are they caused by heparin allergy?

Introduction: Little is known about the incidence and causes of heparin-induced skin lesions. The most commonly reported causes are delayed-type hypersensitivity reactions. We describe 3 patients who were referred to our staff between March and October 2009 for suspected heparin allergies. All were scheduled to undergo major surgery (cardiovascular or orthopedic). Materials and methods: All 3 patients reported the development of itchy, erythematous rashes a few days after the subcutaneous administration of heparin (nadroparin calcium in cases 1 and 2, unspecified in case 3). Each of them underwent a diagnostic work-up for heparin allergy, which included prick and intradermal tests with commonly used heparins and patch testing with undiluted heparins and disinfectants. Results: Patch tests with disinfectants were negative in all 3 cases. In case 2, all allergological tests were negative. In cases 1 and 3, delayed positivity emerged for nadroparin calcium and at least one other heparin tested. Intravenous and/or subcutaneous provocation testing was done with an alternative heparin which produced negative results in skin tests (heparin sodium in case 1, pentasaccharide fondaparinux in case 3). In both cases the alternative drug was tolerated. After our evaluation, all 3 patients underwent surgery with no heparin-related complications. Discussion: The presenting clinical features in these 3 cases provided no information on which reactions were likely to be allergic: all 3 patients presented with similar local delayed reaction. The allergic reactions were identified only after cutaneous testing.

Dynamics of self-generated, large amplitude magnetic fields following high-intensity laser matter interaction

The dynamics of magnetic fields with an amplitude of several tens of megagauss, generated at both sides of a solid target irradiated with a high-intensity (~10(19) W/cm(2)) picosecond laser pulse, has been spatially and temporally resolved using a proton imaging technique. The amplitude of the magnetic fields is sufficiently large to have a constraining effect on the radial expansion of the plasma sheath at the target surfaces. These results, supported by numerical simulations and simple analytical modeling, may have implications for ion acceleration driven by the plasma sheath at the rear side of the target as well as for the laboratory study of self-collimated high-energy plasma jets.

Provocation tests with the offending nonsteroidal anti-inflammatory drugs in patients with urticaria/angioedema reactions

The provocation test (PT) with the suspected drug represents the gold standard in the diagnosis of non-IgE hypersensitivity reactions to nonsteroidal anti-inflammatory drugs (NSAIDs). Nevertheless, there is no consensus regarding the clinical management of suspected NSAID-sensitive patients. This study assessed if a PT with the suspected drug is a reliable and safe proceeding to confirm NSAID hypersensitivity in patients with a clinical history of urticaria/angioedema (Urt/AE). It also analyzed different patient characteristics (such as gender, age, atopy, dermographism, time interval between the last drug reaction, and number of previous NSAID reactions) in relation to PT positivity. One hundred fifty-nine patients with Urt/AE apparently related to assumption of one or more NSAIDs underwent PT with the suspected drugs. Moreover, to distinguish single/multiple NSAID reactivity in patients who did not tolerate the offending NSAID, another strong cyclooxygenase-1 inhibitor PT was performed. PT was negative in 142/159 patients (89.31%), ruling out a diagnosis of NSAIDs hypersensitivity; 17/159 patients (10.69%) experienced a reaction of Urt/AE during the PT: 8 patients were diagnosed as single reactors to NSAIDs and 4 as multiple reactors to NSAIDs. Those with a history of multiple NSAID reactions and male patients were both more likely to have a positive PT. Our results suggest that in all patients with history of NSAID cutaneous reactions, the NSAID hypersensitivity should be confirmed by an oral PT and that the diagnostic proceeding can safely start with the offending NSAID.

Directional limits on persistent gravitational waves using LIGO S5 science data

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

The Piemonte Regional Allergy Network: a model of healthcare organization

The Allergology Hospital Network and Regional Register for Severe Allergic Reactions (Regional Observatory) is the Piemonte Health Authority new challenge. It satisfied the need to promote and monitor the best practice among a variegated pool of specialists and to define both state of the art and evolution of efficiency and efficacy of standard working process. Harmonization in clinical daily activities and report of severe allergic reactions notified to Regional Observatory, had been gained by mean of a customized Information Technology (IT) solution. The overall target is to ensure a correct diagnostic treatment to patients with severe allergic reactions preventing possible future reactions. Statistics data as a whole, provide basilar epidemiological information to allocate both economical and human resources and to fulfill the rising of health diseases. Piemonte Allergology Medical Network with the Regional Register are an Italian unique and innovative project. It would represent a benchmark for other medical branches.

A state observer for the Virgo inverted pendulum

We report an application of Kalman filtering to the inverted pendulum (IP) of the Virgo gravitational wave interferometer. Using subspace method system identification techniques, we calculated a linear mechanical model of Virgo IP from experimental transfer functions. We then developed a Kalman filter, based on the obtained state space representation, that estimates from open loop time domain data, the state variables of the system. This allows the observation (and eventually control) of every resonance mode of the IP mechanical structure independently.

Development of a novel large bandwidth front-end system for high peak power OPCPA systems

We present the development of a laser system capable of generating bandwidths sufficient to support a sub 30 fs pulse at 910 nm. These pulses have been amplified to 500 mJ of energy at 2 Hz in two stages. The contrast measurements show that the initial seed is clean and suggests that the close in contrast is limited by the evaluation stretcher and compressor. Such a system is suitable for seeding high energy high power OPCPA systems based on KD*P.

Magnetically guided fast electrons in cylindrically compressed matter

Fast electrons produced by a 10 ps, 160 J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. K(α)-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter.