Improving Model Generalization by On-manifold Adversarial Augmentation in the Frequency Domain

Deep neural networks (DNNs) may suffer from significantly degenerated performance when the training and test data are of different underlying distributions. Despite the importance of model generalization to out-of-distribution (OOD) data, the accuracy of state-of-the-art (SOTA) models on OOD data can plummet. Recent work has demonstrated that regular or off-manifold adversarial examples, as a special case of data augmentation, can be used to improve OOD generalization. Inspired by this, we theoretically prove that on-manifold adversarial examples can better benefit OOD generalization. Nevertheless, it is nontrivial to generate on-manifold adversarial examples because the real manifold is generally complex. To address this issue, we proposed a novel method of Augmenting data with Adversarial examples via a Wavelet module (AdvWavAug), an on-manifold adversarial data augmentation technique that is simple to implement. In particular, we project a benign image into a wavelet domain. With the assistance of the sparsity characteristic of wavelet transformation, we can modify an image on the estimated data manifold. We conduct adversarial augmentation based on AdvProp training framework. Extensive experiments on different models and different datasets, including ImageNet and its distorted versions, demonstrate that our method can improve model generalization, especially on OOD data. By integrating AdvWavAug into the training process, we have achieved SOTA results on some recent transformer-based models.Comment: Computer Vision and Image Understanding (CVIU) [under review

Upcycling of PET oligomers from chemical recycling processes to PHA by microbial co-cultivation

Polyethylene terephthalate (PET) is the most widely consumed polyester plastic and can be recycled by many chemical processes, of which glycolysis is most cost-effective and commercially viable. However, PET glycolysis produces oligomers due to incomplete depolymerization, which are undesirable by-products and require proper disposal. In this study, the PET oligomers from chemical recycling processes were completely bio-depolymerized into monomers and then used for the biosynthesis of biodegradable plastics polyhydroxyalkanoates (PHA) by cocultivation of two engineered microorganisms Escherichia coli BL21 (DE3)-LCCICCG and Pseudomonas putida KT2440-ΔRDt-ΔZP46C-M. E. coli BL21 (DE3)-LCCICCG was used to secrete the PET hydrolase LCCICCG into the medium to directly depolymerize PET oligomers. P. putida KT2440-ΔRDt-ΔZP46C-M that mastered the metabolism of aromatic compounds was engineered to accelerate the hydrolysis of intermediate products mono-2- (hydroxyethyl) terephthalate (MHET) by expressing IsMHETase, and biosynthesize PHA using ultimate products terephthalate and ethylene glycol depolymerized from the PET oligomers. The population ratios of the two microorganisms during the co-cultivation were characterized by fluorescent reporter system, and revealed the collaboration of the two microorganisms to bio-depolymerize and bioconversion of PET oligomers in a single process. This study provides a biological strategy for the upcycling of PET oligomers and promotes the plastic circular economy

3′,6′-Bis(diethyl­amino)-2-phenyl­spiro[isoindoline-1,9′-xanthen]-3-one

The title compound, C34H35O2N3, was synthesized by the reaction of 2-[3,6-bis­(diethyl­amino)-9H-xanthen-9-yl]benzoyl chloride with aniline. In the mol­ecular structure, the dihedral angles between the isoindoline and xanthene planes and between the isoindoline and benzene planes are 86.9 (3) and 47.0 (2)°, respectively. The mol­ecular packing in the crystal structure is stabilized by weak C—H⋯O hydrogen bonding

Extracellular RNA in a single droplet of human serum reflects physiologic and disease states.

Extracellular RNAs (exRNAs) are present in human serum. It remains unclear to what extent these circulating exRNAs may reflect human physiologic and disease states. Here, we developed SILVER-seq (Small Input Liquid Volume Extracellular RNA Sequencing) to efficiently sequence both integral and fragmented exRNAs from a small droplet (5 μL to 7 μL) of liquid biopsy. We calibrated SILVER-seq in reference to other RNA sequencing methods based on milliliters of input serum and quantified droplet-to-droplet and donor-to-donor variations. We carried out SILVER-seq on more than 150 serum droplets from male and female donors ranging from 18 y to 48 y of age. SILVER-seq detected exRNAs from more than a quarter of the human genes, including small RNAs and fragments of mRNAs and long noncoding RNAs (lncRNAs). The detected exRNAs included those derived from genes with tissue (e.g., brain)-specific expression. The exRNA expression levels separated the male and female samples and were correlated with chronological age. Noncancer and breast cancer donors exhibited pronounced differences, whereas donors with or without cancer recurrence exhibited moderate differences in exRNA expression patterns. Even without using differentially expressed exRNAs as features, nearly all cancer and noncancer samples and a large portion of the recurrence and nonrecurrence samples could be correctly classified by exRNA expression values. These data suggest the potential of using exRNAs in a single droplet of serum for liquid biopsy-based diagnostics

3′,6′-Bis(diethyl­amino)-3H-spiro­[2-benzo­thio­phene-1,9′-xanthene]-3-thione

The title compound, C28H30N2OS2, was obtained by thio­nation of 3′,6′-bis­(diethyl­amino)-3H-spiro­[isobenzofuran-1,9′-xan­thene]-3-one with 2,4-bis­(p-methoxy­phen­yl)-1,3-dithia­diphos­phetane disulfide (Lawesson’s reagent). The planes of the two benzene rings of the xanthene system are inclined at a dihedral angle of 17.4 (1)°, and the plane of the dithio­phthalide group and the planes through the two benzene rings of the xanthene system make dihedral angles of 80.2 (1) and 82.8 (1)°, respectively

Facile synthesis of a nickel sulfide (NiS) hierarchical flower for the electrochemical oxidation of H2O2 and the methanol oxidation reaction (MOR).

The synthesis of a novel hierarchical flower-like NiS via a solvothermal method for the electrochemcial oxidation of H2O2 on a carbon paste electrode with high catalytic activity for the (MOR) in an alkaline medium has been reported. Novel nickel sulfide (NiS) hierarchical flower-like structures were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. A carbon paste electrode was modified with the as-prepared hierarchical flower-like NiS, resulting in a high electrocatalytic activity toward the oxidation of H2O2. The NiS-modified electrode was used for H2O2 sensing, which was achieved over a wide linear range from 0.5 μMto1.37mM(I/μA =-0.19025 + 0.06094 C/mM) with a low limit of detection (LOD) of 0.3 μM and a limit of quantitation (LOQ) of 0.8 μM. The hierarchical flower-like NiS also exhibited a high electrocatalytic activity for the methanol oxidation reaction (MOR) in an alkaline medium with a high tolerance toward the catalyst-poisoning species generated during the MOR. The MOR proceeded via the direct electrooxidation of methanol on the oxidized NiS surface layer because the oxidation peak potential of the MOR was more positive than that of the oxidation of NiS