Perspectives in three-dimensional analysis of bone samples using synchrotron radiation microtomography

International audienceIn this paper we present a methodology based on 3D synchrotron radiation microtomography to analyze non-destructively 3D bone samples. After a technical presentation of the imaging system and the image analysis techniques, we report results on three-dimensional analysis of vertebral samples from women of different ages. The new capabilities of this technique for the investigation of bone are discussed. They include a high spatial resolution down to the micron level, a high density resolution allowing a local quantification of bone mineralization, phase contrast imaging and advances in 3D image analysis

Observation of microstructure and damage in materials by phase sensitive radiography and tomography

International audienceThe novel possibilities of phase feature detection in radiography at a third generation synchrotron radiation source are used to image, both in projection and in computed tomography, a cracked silicon single crystal and metal matrix composites strained in tension. Through an instrumentally very simple technique, based on Fresnel diffraction, phase jumps related to the interface between the matrix and the reinforcing phases of the composites are detected even when these phases show very similar x-ray attenuation. Strain-induced cracks with openings below the micrometer range are also visible through the phase modulation they introduce, illustrating the potential of the technique for assessing damage in materials with improved resolution and sensitivity

Micro‐CT examinations of trabecular bone samples at different resolutions: 14, 7 and 2 micron level

International audienceTomographic techniques are attractive for the investigation of trabecular bone architecture. Using either conventional X‐ray sources or synchrotron sources currently allows the acquisition of 3D images in a wide range of spatial resolution that may be as small as a few micrometers. Since it is technically possible to examine trabecular architecture at different scales, a question is to know what type of information it is possible to get at each scale. For this purpose, a series of ten vertebrae samples from healthy females of different ages (33 to 90) was imaged at various resolutions on three different micro‐CT systems (cubic voxel size respectively 14, 6.7 and 1.4 \mum). The comparison of morphometric parameters extracted from the different images is in agreement with simulation results on the influence of spatial resolution on structure parameters. The conclusion is that a 14 \mum voxel size gives a reasonably good parameterisation of trabecular architecture. Besides the synchrotron radiation 2 \mum level images reveal interesting features on the irregularities and rupture of trabecular surface, and on remodeling zones

CO in the ALMA Radio-Source Catalogue (ARC): the molecular gas content of radio galaxies as a function of redshift

To evaluate the role of radio activity in galaxy evolution, we designed a large archival CO survey of radio galaxies (RGs) to determine their molecular gas masses at different epochs. We used a sample of 120 RGs representative of the NVSS 1.4 GHz survey, when flux limited at 0.4 Jy. Of those, 66 galaxies belonged to the ALMA Radio-source Catalogue (ARC) of calibrators and had spectral window tunings around CO (1-0), (2-1), (3-2), or (4-3). We reduced their ALMA data, determined their H2 mass contents, and combined the results with similar results for the remaining 54 galaxies from the literature. We found that, while at all epochs the majority of RGs have undetectable reservoirs, there is a rapid increase in the H2 mass content of the CO-detected RGs with z. At 1<z<2.5, one-fourth of the RGs have at least as much molecular gas as simulations would indicate for a typical halo mass of that epoch. These galaxies plausibly have ``normal'' or even starburst hosts. Taking into account the completeness correction of the sample, we created the corresponding H$_2$ mass functions at 0.005<z<0.3 and 1<z<2.5. The local mass function reveals that the number density of low-z RGs with detectable molecular gas reservoirs is only a little lower (a factor of ~4) than that of pure (or little star-forming) type 1 and 2 AGN in simulations. At 1<z<2.5, there is a significant decrease in the number density of high-z RGs due to the rarity of bright radio galaxies. An estimate for the missing faint RGs would, nonetheless, bring populations close again. Finally, we find that the volume density of molecular gas locked up in the brightest 1/5000-1/7000 RGs is similar in the examined $z$ bins. This result likely indicates that the inflow rate on one hand and the star-formation depletion rate plus the jet-driven expulsion rate on the other hand counteract each other in the most luminous RGs of each epoch.Comment: 21 pages, 10 figure

Phthalocyanine–Perylenediimide Cart Wheels

The electronic features of Zn­(II) and Ru­(II) phthalo­cyanines (Pcs) have been modulated by direct peripheral attachment of up to eight ferrocenes. The presence of peripheral ferrocenes noticeably impacts the electronic properties of the corresponding ZnPc and RuPc complexes <b>7</b>, <b>12</b> and <b>9</b>, <b>15</b>, respectivelya notion that is supported by optical spectroscopy with bathochromic shifts of up to 8–10 nm per ferrocene unit. Cyclic voltammetry and optical spectroscopy reveal long-distance (10–11 bonds) electronic interaction between ferrocene units. The ZnPc and RuPc complexes have been integrated into a series of orthogonal, supramolecular bis­(phthalo­cyanine)–perylene­diimide electron donor–acceptor conjugates, <b>2a,b</b> and <b>3a,b</b>. In these cart-wheel-shaped arrays, coordination of ditopic perylene­diimide <b>16</b>, containing two pyridyl substituents at its imido positions, enabled selective interactions with the metal centers of phthalo­cyanines <b>7</b>, <b>12</b>, <b>9</b>, and <b>15</b>. The presence of ferrocenes in, for example, Zn complexes <b>2a</b> and <b>3a</b> triggers a fast energy transfer from the excited-state PDI to ZnPc. In the RuPc-PDI conjugates, substitution with ferrocenes produces a slight acceleration of the charge separation upon photoexcitation of the PDI chromophore. However, charge recombination is accelerated by 2 orders of magnitude in ferrocene-containing conjugates when compared to that in the analogous <i>tert</i>-butyl-substituted array <b>1b</b>

A Green-to-Near-Infrared Photoswitch Based on a Blended Subporphyrazine–Dithienylethene System

A subporphyrazine (SubPz)–dithienylethene (DTE) photochromic device with 1o and 1c states, was developed and characterized. In this device, the DTE unit can reversibly switch the SubPz absorbance from green to near-infrared [λmax (o/c) = 527 nm/740 nm], as well as the SubPz fluorescence and singlet oxygen quantum yields. The core of this design involves using a highly tunable SubPz chromophore that shares its quasi-isolated ethene moiety with a DTE photoswitch

Boosting the Impact of EFMC Young Scientists Network Through the Creation of Working Groups

The establishment of the Young Scientists Network (YSN) by the European Federation for Medicinal Chemistry (EFMC) served as a proactive response to the evolving landscape of the scientific community. The YSN aims to assist early-career medicinal chemists and chemical biologists by responding to emerging themes, such as the influence of social media, shifts in gender balance within the scientific population, and evolving educational opportunities. The YSN also ensures that the upcoming generation of scientists actively contributes to shape the EFMC's strategic direction while addressing their specific needs. Initially conceived as a general concept, YSN has evolved into a proactive and dynamic team which demonstrates a tangible impact. To boost the impact of the YSN and involve additional motivated young scientists, we have adopted a novel organization, and structured the team in seven working groups (WGs). Herein, we will discuss the tasks of the different WGs as well as the activities planned for the near future. We believe this structure will strengthen the pivotal role YSN has already played in serving medicinal chemists and chemical biologists in Europe. The YSN now has the structure and motivation to pave the way to attract young scientists across Europe and to give them the stage within EFMC

A Green-to-Near-Infrared Photoswitch Based on a Blended Subporphyrazine–Dithienylethene System

A subporphyrazine (SubPz)–dithienylethene (DTE) photochromic device with 1o and 1c states, was developed and characterized. In this device, the DTE unit can reversibly switch the SubPz absorbance from green to near-infrared [λmax (o/c) = 527 nm/740 nm], as well as the SubPz fluorescence and singlet oxygen quantum yields. The core of this design involves using a highly tunable SubPz chromophore that shares its quasi-isolated ethene moiety with a DTE photoswitch

Ultrafast Photoinduced Processes in Subphthalocyanine Electron Donor–Acceptor Conjugates Linked by a Single B–N Bond

We have prepared two different subphthalocyanine conjugates by linking these macrocycles either to an electron-accepting perylene diimide or to an electron-donating phenothiazine through a single B–N covalent bond. The short spacing between the two active building blocks results in ultrafast photoinduced electron-transfer reactions

A Green-to-Near-Infrared Photoswitch Based on a Blended Subporphyrazine–Dithienylethene System

A subporphyrazine (SubPz)–dithienylethene (DTE) photochromic device with 1o and 1c states, was developed and characterized. In this device, the DTE unit can reversibly switch the SubPz absorbance from green to near-infrared [λmax (o/c) = 527 nm/740 nm], as well as the SubPz fluorescence and singlet oxygen quantum yields. The core of this design involves using a highly tunable SubPz chromophore that shares its quasi-isolated ethene moiety with a DTE photoswitch