Generative Adversarial Mapping Networks

Generative Adversarial Networks (GANs) have shown impressive performance in generating photo-realistic images. They fit generative models by minimizing certain distance measure between the real image distribution and the generated data distribution. Several distance measures have been used, such as Jensen-Shannon divergence, $f$-divergence, and Wasserstein distance, and choosing an appropriate distance measure is very important for training the generative network. In this paper, we choose to use the maximum mean discrepancy (MMD) as the distance metric, which has several nice theoretical guarantees. In fact, generative moment matching network (GMMN) (Li, Swersky, and Zemel 2015) is such a generative model which contains only one generator network $G$ trained by directly minimizing MMD between the real and generated distributions. However, it fails to generate meaningful samples on challenging benchmark datasets, such as CIFAR-10 and LSUN. To improve on GMMN, we propose to add an extra network $F$, called mapper. $F$ maps both real data distribution and generated data distribution from the original data space to a feature representation space $\mathcal{R}$, and it is trained to maximize MMD between the two mapped distributions in $\mathcal{R}$, while the generator $G$ tries to minimize the MMD. We call the new model generative adversarial mapping networks (GAMNs). We demonstrate that the adversarial mapper $F$ can help $G$ to better capture the underlying data distribution. We also show that GAMN significantly outperforms GMMN, and is also superior to or comparable with other state-of-the-art GAN based methods on MNIST, CIFAR-10 and LSUN-Bedrooms datasets.Comment: 9 pages, 7 figure

Cu/Mn Co-oxidized Cyclization for the Synthesis of Highly Substituted Pyrrole Derivatives from Amino Acid Esters: A Strategy for the Biomimetic Syntheses of Lycogarubin C and Chromopyrrolic Acid

An effective and concise approach to synthesis of tetrasubstituted pyrroles from readily available amino acid esters by the promotion of Cu­(OAc)₂ in conjunction with Mn­(OAc)₃ has been developed. This reaction proceeds through multiple dehydrogenations, deamination, and oxidative cyclization. This oxidized system tolerates substrates bearing various electron-donating or electron-withdrawing groups. With this methodology, several key intermediates of natural products have been effectively prepared, and the total syntheses of lycogarubin C and chromopyrrolic acid have been completed in high efficiency

Triptycene-Derived Homooxacalixarene Analogues: Synthesis, Structures, and Complexation with Fullerenes C₆₀ and C₇₀

A series of triptycene-derived homooxacalixarene analogues were conveniently synthesized by a one-pot approach starting from 2,7-dihydroxytriptycene and 1,3-bisbromomethylbenzene derivatives under mild reaction conditions. Similarly, two pairs of “basket-like” triptycene-derived homooxacalixarene analogues were also designed and synthesized. Structures of these macrocyclic molecules in both solution and solid state were studied by NMR experiments and X-ray crystallography. Because of the rigid triptycene units, the homooxacalixarene analogues showed large cavities and fixed conformations even up to 380 K. It was also found that these novel macrocycles could be served as efficient host molecules for complexation with fullerenes C₆₀ and C₇₀

Triptycene-Derived Homooxacalixarene Analogues: Synthesis, Structures, and Complexation with Fullerenes C₆₀ and C₇₀

A series of triptycene-derived homooxacalixarene analogues were conveniently synthesized by a one-pot approach starting from 2,7-dihydroxytriptycene and 1,3-bisbromomethylbenzene derivatives under mild reaction conditions. Similarly, two pairs of “basket-like” triptycene-derived homooxacalixarene analogues were also designed and synthesized. Structures of these macrocyclic molecules in both solution and solid state were studied by NMR experiments and X-ray crystallography. Because of the rigid triptycene units, the homooxacalixarene analogues showed large cavities and fixed conformations even up to 380 K. It was also found that these novel macrocycles could be served as efficient host molecules for complexation with fullerenes C₆₀ and C₇₀

Triptycene-Derived Homooxacalixarene Analogues: Synthesis, Structures, and Complexation with Fullerenes C₆₀ and C₇₀

A series of triptycene-derived homooxacalixarene analogues were conveniently synthesized by a one-pot approach starting from 2,7-dihydroxytriptycene and 1,3-bisbromomethylbenzene derivatives under mild reaction conditions. Similarly, two pairs of “basket-like” triptycene-derived homooxacalixarene analogues were also designed and synthesized. Structures of these macrocyclic molecules in both solution and solid state were studied by NMR experiments and X-ray crystallography. Because of the rigid triptycene units, the homooxacalixarene analogues showed large cavities and fixed conformations even up to 380 K. It was also found that these novel macrocycles could be served as efficient host molecules for complexation with fullerenes C₆₀ and C₇₀

Triptycene-Derived Homooxacalixarene Analogues: Synthesis, Structures, and Complexation with Fullerenes C₆₀ and C₇₀

A series of triptycene-derived homooxacalixarene analogues were conveniently synthesized by a one-pot approach starting from 2,7-dihydroxytriptycene and 1,3-bisbromomethylbenzene derivatives under mild reaction conditions. Similarly, two pairs of “basket-like” triptycene-derived homooxacalixarene analogues were also designed and synthesized. Structures of these macrocyclic molecules in both solution and solid state were studied by NMR experiments and X-ray crystallography. Because of the rigid triptycene units, the homooxacalixarene analogues showed large cavities and fixed conformations even up to 380 K. It was also found that these novel macrocycles could be served as efficient host molecules for complexation with fullerenes C₆₀ and C₇₀

Healable, Reconfigurable, Reprocessable Thermoset Shape Memory Polymer with Highly Tunable Topological Rearrangement Kinetics

The unique capability of topological rearrangement for dynamic covalent polymer networks has enabled various unusual properties (self-healing, solid-state plasticity, and reprocessability) that are not found in conventional thermosets. Achieving these properties in one network in a synergetic fashion can open up new opportunities for shape memory polymer. To accomplish such a goal, the freedom to tune topological rearrangement kinetics is critical. This is, however, challenging to achieve. In this work, two sets of dynamic bonds (urethane and hindered urea) are incorporated into a hybrid network for synthesizing shape memory poly­(urea-urethane). By changing the bond ratio, networks with highly tunable topological rearrangement kinetics are obtained. Combining self-healing, solid-state plasticity, and reprocessability in one such shape memory network leads to unusual versatility in its shape-shifting performance

Microstructured Shape Memory Polymer Surfaces with Reversible Dry Adhesion

We present a shape memory polymer (SMP) surface with repeatable, very strong (>18 atm), and extremely reversible (strong to weak adhesion ratio of >1 × 10⁴) dry adhesion to a glass substrate. This was achieved by exploiting bulk material properties of SMP and surface microstructuring. Its exceptional dry adhesive performance is attributed to the SMP’s rigidity change in response to temperature and its capabilities of temporary shape locking and permanent shape recovery, which when combined with a microtip surface design enables time-independent control of contact area

Three-Phase Catassembly of 10 nm Au Nanoparticles for Sensitive and Stable Surface-Enhanced Raman Scattering Detection

Interfacial self-assembly with the advantage of providing large-area, high-density plasmonic hot spots is conducive to achieving high sensitivity and stable surface-enhanced Raman scattering (SERS) sensing. However, rapid and simple assembly of highly repeatable large-scale multilayers with small nanoparticles remains a challenge. Here, we proposed a catassembly approach, where the “catassembly” means the increase in the rate and control of nanoparticle assembly dynamics. The catassembly approach was dropping heated Au sols onto oil chloroform (CHCl3), which triggers a rapid assembly of plasmonic multilayers within 15 s at the oil–water–air (O/W/A) interface. A mixture of heated sol and CHCl3 constructs a continuous liquid–air interfacial tension gradient; thus, the plasmonic multilayer film can form rapidly without adding functional ligands. Also, the dynamic assembly process of the three-phase catassembly ranging from cluster to interfacial film formation was observed through experimental characterization and COMSOL simulation. Importantly, the plasmonic multilayers of 10 nm Au NPs for SERS sensing demonstrated high sensitivity with the 1 nM level for crystal violet molecules and excellent stability with an RSD of about 10.0%, which is comparable to the detection level of 50 nm Au NPs with layer-by-layer assembly, as well as breaking the traditional and intrinsic understanding of small particles of plasmon properties. These plasmonic multilayers of 10 nm Au NPs through the three-phase catassembly method illustrate high SERS sensitivity and stability, paving the way for small-nanoparticle SERS sensing applications

Three-Phase Catassembly of 10 nm Au Nanoparticles for Sensitive and Stable Surface-Enhanced Raman Scattering Detection

Interfacial self-assembly with the advantage of providing large-area, high-density plasmonic hot spots is conducive to achieving high sensitivity and stable surface-enhanced Raman scattering (SERS) sensing. However, rapid and simple assembly of highly repeatable large-scale multilayers with small nanoparticles remains a challenge. Here, we proposed a catassembly approach, where the “catassembly” means the increase in the rate and control of nanoparticle assembly dynamics. The catassembly approach was dropping heated Au sols onto oil chloroform (CHCl3), which triggers a rapid assembly of plasmonic multilayers within 15 s at the oil–water–air (O/W/A) interface. A mixture of heated sol and CHCl3 constructs a continuous liquid–air interfacial tension gradient; thus, the plasmonic multilayer film can form rapidly without adding functional ligands. Also, the dynamic assembly process of the three-phase catassembly ranging from cluster to interfacial film formation was observed through experimental characterization and COMSOL simulation. Importantly, the plasmonic multilayers of 10 nm Au NPs for SERS sensing demonstrated high sensitivity with the 1 nM level for crystal violet molecules and excellent stability with an RSD of about 10.0%, which is comparable to the detection level of 50 nm Au NPs with layer-by-layer assembly, as well as breaking the traditional and intrinsic understanding of small particles of plasmon properties. These plasmonic multilayers of 10 nm Au NPs through the three-phase catassembly method illustrate high SERS sensitivity and stability, paving the way for small-nanoparticle SERS sensing applications