Publications

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

The goal of this paper is to take a single 2D image of a scene and recover the 3D structure in terms of a small set of factors: a layout representing the enclosing surfaces as well as a set of objects represented in terms of shape and pose. We propose a convolutional neural network-based approach to predict this representation and benchmark it on a large dataset of indoor scenes. Our experiments evaluate a number of practical design questions, demonstrate that we can infer this representation, and quantitatively and qualitatively demonstrate its merits compared to alternate representations.

All that structure from motion algorithms "see" are sets of 2D points. We show that these impoverished views of the world can be faked for the purpose of reconstructing objects in challenging settings, such as from a single image, or from a few ones far apart, by recognizing the object and getting help from a collection of images of other objects from the same class. We synthesize virtual views by computing geodesics on novel networks connecting objects with similar viewpoints, and introduce techniques to increase the specificity and robustness of factorization-based object reconstruction in this setting. We report accurate object shape reconstruction from a single image on challenging PASCAL VOC data, which suggests that the current domain of applications of rigid structure-from-motion techniques may be significantly extended.

The dynamics of structural transformations of Pt aggregates in the "quantum size" range where their molecular structure transforms into crystalline nanoparticles with metallic properties is an important issue in nanoscience. Here, we show high-resolution transmission electron microscopy (HRTEM) and spectroscopic observations of the polyamidoamine (PAMAM) dendrimer-mediated system, Pt–PAMAM, after UV irradiation that reveal the formation of small Ptδ+n clusters (n = 2–8) with linear chains of −Pt–Pt–, which are the building blocks of stable nanocrystals. Dynamic imaging in an aberration corrected TEM at atomic resolution shows intermediate molecular and crystalline states and coalescence of Pt clusters into stable nanocrystals via an oriented attachment assembly process. We propose that the structural transformation from Pt aggregates to nanocrystals occurs between 1.5 and 2 nm and that a phase transition of the type "disordered-to-crystalline" exists depending on the number of atoms in the cluster.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

New Li0.9Ni0.45Ti0.55O2 positive electrode materials were synthesized by means of ion exchange from Na0.9Ni0.45Ti0.55O2. Powder X-ray diffraction (XRD) patterns for these materials indicate that they are isostructural with -NaFeO2. The degree of cation disordering in the material depends critically on the synthesis conditions. Higher temperatures and longer ion-exchange times induce more cation disordering. Surprisingly, the partially disordered phase shows better capacity retention than the least disordered phase. First-principles calculations indicated the poor capacity retention in the least disordered phase could be attributed to the migration of Ti4+ into the Li layer during the electrochemical testing...

SNhunt151 was initially classified as a supernova (SN) impostor (nonterminal outburst of a massive star). It exhibited a slow increase in luminosity, lasting about 450 d, followed by a major brightening that reaches M_V ≈ −18 mag. No source is detected to M_V ≳ −13 mag in archival images at the position of SNhunt151 before the slow rise. Low-to-mid-resolution optical spectra obtained during the pronounced brightening show very little evolution, being dominated at all times by multicomponent Balmer emission lines, a signature of interaction between the material ejected in the new outburst and the pre-existing circumstellar medium. We also analysed mid-infrared images from the Spitzer Space Telescope, detecting a source at the transient position in 2014 and 2015. Overall, SNhunt151 is spectroscopically a Type IIn SN, somewhat similar to SN 2009ip. However, there are also some differences, such as a slow pre-discovery rise, a relatively broad light-curve peak showing a longer rise time (∼50 d), and a slower decline, along with a negligible change in the temperature around the peak (T ≤ 10^4 K). We suggest that SNhunt151 is the result of an outburst, or an SN explosion, within a dense circumstellar nebula, similar to those embedding some luminous blue variables like η Carinae and originating from past mass-loss events.

The development of protein-based vaccines remains a major challenge in the fields of immunology and drug delivery. Although numerous protein antigens have been identified that can generate immunity to infectious pathogens, the development of vaccines based on protein antigens has had limited success because of delivery issues. In this article, an acid-sensitive microgel material is synthesized for the development of protein-based vaccines. The chemical design of these microgels is such that they degrade under the mildly acidic conditions found in the phagosomes of antigen-presenting cells (APCs). The rapid cleavage of the microgels leads to phagosomal disruption through a colloid osmotic mechanism, releasing protein antigens into the APC cytoplasm for class I antigen presentation. Ovalbumin was encapsulated in microgel particles, 200–500 nm in diameter, prepared by inverse emulsion polymerization with a synthesized acid-degradable crosslinker. Ovalbumin is released from the acid-degradable microgels in a pH-dependent manner; for example, microgels containing ovalbumin release 80% of their encapsulated proteins after 5 h at pH 5.0, but release only 10% at pH 7.4. APCs that phagocytosed the acid-degradable microgels containing ovalbumin were capable of activating ovalbumin-specific cytoxic T lymphocytes. The acid-degradable microgels developed in this article should therefore find applications as delivery vehicles for vaccines targeted against viruses and tumors, where the activation of cytoxic T lymphocytes is required for the development of immunity.