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Microgels are water‐swollen, crosslinked polymers that are widely used as colloidal building blocks in scaffold materials for tissue engineering and regenerative medicine. Microgels can be controlled in their stiffness, degree of swelling, and mesh size depending on their polymer architecture, crosslink density, and fabrication method—all of which influence their function and interaction with the environment. Currently, there is a lack of understanding of how the polymer composition influences the internal structure of soft microgels and how this morphology affects specific biomedical applications. In this report, we systematically vary the architecture and molar mass of polyethylene glycol‐acrylate (PEG‐Ac) precursors, as well as their concentration and combination, to gain insight in the different parameters that affect the internal structure of rod‐shaped microgels. We characterize the mechanical properties and diffusivity, as well as the conversion of acrylate groups during photopolymerization, in both bulk hydrogels and microgels produced from the PEG‐Ac precursors. Furthermore, we investigate cell‐microgel interaction, and we observe improved cell spreading on microgels with more accessible RGD peptide and with a stiffness in a range of 20 kPa to 50 kPa lead to better cell growth. [ABSTRACT FROM AUTHOR]

The correlation of mechanical properties of polymer materials with those of their molecular constituents is the foundation for their holistic comprehension and eventually for improved material designs and syntheses. Over the last decade, optical force probes (OFPs) were developed, shedding light on various unique mechanical behaviors of materials. The properties of polymers are diverse, ranging from soft hydrogels to ultra‐tough composites, from purely elastic rubbers to viscous colloidal solutions, and from transparent glasses to super black dyed coatings. Only very recently, researchers started to develop tailored OFP solutions that account for such material requirements in energy (both light and force), in time, and in their spatially detectable resolution. We here highlight notable recent examples and identify future challenges in this emergent field. [ABSTRACT FROM AUTHOR]

The fracture of polymer materials is a multiscale process starting with the scission of a single molecular bond advancing to a site of failure within the bulk. Quantifying the bonds broken during this process remains a big challenge yet would help to understand the distribution and dissipation of macroscopic mechanical energy. We here show the design and synthesis of fluorogenic molecular optical force probes (mechanofluorophores) covering the entire visible spectrum in both absorption and emission. Their dual fluorescent character allows to track non‐broken and broken bonds in dissolved and bulk polymers by fluorescence spectroscopy and microscopy. Importantly, we develop an approach to determine the absolute number and relative fraction of intact and cleaved bonds with high local resolution. We anticipate that our mechanofluorophores in combination with our quantification methodology will allow to quantitatively describe fracture processes in materials ranging from soft hydrogels to high‐performance polymers. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the American Institute for Conservation is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The remarkable optical properties of a hybrid structure consisting of a silver nanowire (NW) densely decorated with silver nanoparticles (NPs) are described. Silver NWs densely decorated with silver NPs, self-assembled by a simple wet-chemical method has displayed well-separated and fairly regular hot-spots of localized surface plasmon resonances (LSPRs).

The surface-enhanced Raman spectra (SERS) of pyrimidine recorded on a silver electrode is analyzed based on the resonant Raman (RR) process involving photoexcited charge transfer (CT) states of the metal-adsorbate surface complex. The results have confirmed the relevance of CT mechanism in the SERS of aromatic molecules and have also highlighted the origin of the SERS phenomenon.

The article presents technical analyses of three portrait paintings by 20th century artist Amedeo Modigliani, "Portrait of a Young Woman," "Head of Jeanne Hébuterne" and "Jeanne Hébuterne." It analyzes the style and painting techniques used by Modigliani in his late portraits. The artist's use of a limited palette of common pigments is discussed, as well as the distinctive features of the paintings.

The article presents technical analyses of three paintings by 20th century artist Amedeo Modigliani, " The Little Peasant," "Young Woman of the People" and "The Italian Woman." It examines a change in the technique and appearance of paintings by Modigliani towards the end of World War I. The artist's use of a few basic pigments and non oil-based paint for his portrait paintings is discussed.

Analyses of two samples of the commercial platinum photographic paper 'Japine' revealed that this trade-name product was sold with a range of surface properties from matte to glossy. An in-depth examination of an unprocessed glossy Japine sample showed a chemically modified surface resulting from parchmentization by treatment with sulfuric acid. This treatment results in a thin film of amorphous cellulose on the printing surface, altering its visual appearance and wet strength. Photographers selected this paper due to its aesthetic qualities. However, such papers have never been characterized and are essentially unknown to modern-day scholars who may mistake them as prints with thin binder layers, such as albumen or gelatin. Indeed, the approach to conservation of these photographs may differ from one designed for a traditional platinum print. The parchmentized Japine paper was criticized for its tendency to crack, one characteristic that may have implications for its handling and conservation treatment today. [ABSTRACT FROM AUTHOR]

Jacopo Bassano's last altarpiece, the Baptism of Christ, has recently entered the collection of The Metropolitan Museum of Art. The painting was left in the artist's studio at his death, and listed in the inventory drawn up in 1592 as ‘una Tavola d'altare sbozzata' (Ridolfi, writing in 1648, used the term ‘non finita' to describe it). It was kept by the family until 1673, and only then did they sell it to another family from Bassano, with whom it remained until late in the following century. Re-discovered in the 1930s, it has since been recognized as one of the most moving and personal of Jacopo's late works, deviating from tradition both in its nocturnal setting and dramatic sense of foreboding. As the Baptism has just undergone cleaning and conservation, as well as a technical examination including infra-red reflectography, X-radiography, and pigment analysis under the direction of Michael Gallagher (Chair, Department of Paintings Conservation), this is a propitious moment to look at it again, reassessing Bassano's approach to the subject and the altarpiece's place within the artist's later career. Cleaning and treatment have confirmed the extraordinary, painterly quality of the work, leading to significant new observations about his technique and the issue of ‘non finito' in his late paintings. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the American Institute for Conservation is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the late 1800s, pictorialist photographers favored a diversity of photographic techniques, including the gum dichromate process. Sometimes superimposed over other photographic images such as platinum and silver prints, the gum dichromate process utilizes a light-sensitive mixture of gum arabic, pigment, and a potassium dichromate solution hand-applied onto a sheet of paper and exposed to light while in direct contact with a negative. The definitive identification of this process has proven to be a challenge due to many variations and intermingling of techniques used by photographers of this period. This research began with a search through the historic literature, followed by the creation of test samples based on historic recipes, and the X-ray fluorescence analysis of these tests. The identification of pigments and the presence of chromium have been associated with the gum dichromate or other dichromated colloid processes in the past. Research results reveal that the presence of chromium may have more complex sources, requiring a more discriminating approach and a modified protocol for the identification of gum dichromate photographs. [ABSTRACT FROM AUTHOR]

The marble of the New York Public Library was found to be in a fairly good state of conservation except for the more exposed elements, such as quoins and the many delicately carved elements that decorate the building. This paper focuses on the treatment developed for areas that showed significant sugaring. For this purpose, laboratory examinations and analyses were carried out and preliminary tests were made with silicate ester-based consolidants. These, however, did not perform well in test studies and therefore an approach using inorganic materials was developed. The treatment consisted of spray application of an ammonium oxalate solution that reduced the intensive sugaring of the marble. To further protect these eroded surfaces, a shelter coat based on Type S hydrated dolomitic lime was also applied. This method is fully compatible with the marble substrate and follows the overriding principle of minimum intervention, as stated by the Venice Charter. [ABSTRACT FROM AUTHOR]

Chemiluminescence, fluorescence, mechanochemistry, polymers, sensors Keywords: chemiluminescence; fluorescence; mechanochemistry; polymers; sensors EN chemiluminescence fluorescence mechanochemistry polymers sensors 1 1 1 11/19/21 20211117 NES 211117 B Optical force probes (OFPs) b shine light on various unique mechanical behaviors of materials and allow the correlation of macroscopic mechanical properties with those of their molecular constituents. [Extracted from the article]

Chemiluminescence, fluorescence, mechanochemistry, polymers, sensors Keywords: chemiluminescence; fluorescence; mechanochemistry; polymers; sensors EN chemiluminescence fluorescence mechanochemistry polymers sensors 15823 15823 1 11/19/21 20211117 NES 211117 B As potential analytical tools b for collecting and mapping mechanical information in polymer materials, optical force probes (OFPs) have been developed over the last decade. [Extracted from the article]

The article presents a technical examination of John Singer's portrait painting of Madame Pierre Gautreau titled "Portrait of Madame X" in 1884 Details of how Sargent approached Gautreau requesting to paint her are given. Through X-radiography, the extent of Sargent's numerous adjustments made on the painting, most notably to the position of head and arms, were revealed. Thorough inspection of the head reveals at least 8 profiles moving right to left. Singer's intention, at an early stage, to put the strap over the shoulder was revealed by the dark shadow on the right shoulder.

Surface-enhanced Raman scattering spectra of 2,4,6-trimethylpyridine recorded on silver at different electrode potentials have been analyzed on the basis of a charge transfer enhancement mechanism. The main feature of surface-enhanced Raman scattering is the enhancement of the band corresponding to the 8a mode at negative electrode potentials. This behavior can be explained by Franck–Condon factors related to a photoinduced electron transfer process between the metal and the adsorbate. The selective surface-enhanced Raman scattering enhancement is related to the differences between the ab initio equilibrium geometries of the electronic levels involved in the resonant mechanism, i.e., the ground states of the neutral adsorbate and the respective radical anion. [Copyright &y& Elsevier]

A systematic method to fit calculated to observed vibrational frequencies has been developed and implemented in a computer program. The procedure consists of the refinement of a scaled quantum mechanical force field (SQMFF) previously obtained according to Pulay's method. The key step in the process is the generation of an intermediate matrix, CΛC[sup T], which is then refined. The above step produces only small corrections to the scaled force constants, yielding a considerable improvement of the fitted frequencies. This scheme of refinement can be carried out using any kind of coordinates. To show the reliability and performance of the proposed method, the force fields of two very different systems, as benzene and tetranitromethane, have been chosen as example tests. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]