Plasmonic Hotspots in Air: An Omnidirectional Three‐Dimensional Platform for Stand‐Off In‐Air SERS Sensing of Airborne Species

Molecular‐level airborne sensing is critical for early prevention of disasters, diseases, and terrorism. Currently, most 2D surface‐enhanced Raman spectroscopy (SERS) substrates used for air sensing have only one functional surface and exhibit poor SERS‐active depth. “Aerosolized plasmonic colloidosomes” (APCs) are introduced as airborne plasmonic hotspots for direct in‐air SERS measurements. APCs function as a macroscale 3D and omnidirectional plasmonic cloud that receives laser irradiation and emits signals in all directions. Importantly, it brings about an effective plasmonic hotspot in a length scale of approximately 2.3 cm, which affords 100‐fold higher tolerance to laser misalignment along the z‐axis compared with 2D SERS substrates. APCs exhibit an extraordinary omnidirectional property and demonstrate consistent SERS performance that is independent of the laser and analyte introductory pathway. Furthermore, the first in‐air SERS detection is demonstrated in stand‐off conditions at a distance of 200 cm, highlighting the applicability of 3D omnidirectional plasmonic clouds for remote airborne sensing in threatening or inaccessible areas.     

Toward efficient catalysts for electrochemical CO2 conversion to C2 products

With impressive progress in carbon capture and renewable energy, carbon dioxide (CO₂) conversion into useful chemicals has become a potential tool against climate change. Electrochemical CO₂ conversion into C₂ products (ethylene and ethanol) is an especially economically promising approach and an active research area. Nonetheless, catalyst layer design for CO₂ conversion is challenging because of the complex CO₂-to-C₂ reaction pathways. In this review, we highlight key ideas in catalyst layer design for CO₂ conversion to C₂ in the past few years. We identify three fundamental principles to control catalyst selectivity—local CO₂ and CO concentration, local pH, and intermediate–catalyst interaction. To achieve these goals, we introduce design strategies for both catalytic materials and overall catalyst layer morphology.     

Secondary Metabolites from the Fruiting Bodies of Coriolopsis aspera in Vietnam and their Bioactivities

Chemistry of Natural Compounds -     

Large‐Area Synthesis of Superclean Graphene via Selective Etching of Amorphous Carbon with Carbon Dioxide

Contamination commonly observed on the graphene surface is detrimental to its excellent properties and strongly hinders its application. It is still a great challenge to produce large‐area clean graphene film in a low‐cost manner. Herein, we demonstrate a facile and scalable chemical vapor deposition approach to synthesize meter‐sized samples of superclean graphene with an average cleanness of 99 %, relying on the weak oxidizing ability of CO₂ to etch away the intrinsic contamination, i.e., amorphous carbon. Remarkably, the elimination of amorphous carbon enables a significant reduction of polymer residues in the transfer of graphene films and the fabrication of graphene‐based devices and promises strongly enhanced electrical and optical properties of graphene. The facile synthesis of large‐area superclean graphene would open the pathway for both fundamental research and industrial applications of graphene, where a clean surface is highly needed.     

A Simplified Method for the Measurement of Insoluble Solids in Pretreated Biomass Slurries

The biochemical conversion of cellulosic biomass to liquid transportation fuels includes the breakdown of biomass into its soluble, fermentable components. Pretreatment, the initial step in the conversion process, results in heterogeneous slurry comprised of both soluble and insoluble biomass components. For the purpose of tracking the progress of the conversion process, it is important to be able to accurately measure the fraction of insoluble biomass solids in the slurry. The current standard method involves separating the solids from the free liquor and then repeatedly washing the solids to remove the soluble fraction, a laborious and tedious process susceptible to operator variations. In this paper, we propose an alternative method for calculating the fraction of insoluble solids which does not require a washing step. The proposed method involves measuring the dry matter content of the whole slurry as well as the dry matter content in the isolated liquor fraction. We compared the two methods using three different pretreated biomass slurry samples and two oven-drying techniques for determining dry matter content, an important measurement for both methods. We also evaluated a large set of fraction insoluble solids data collected from previously analyzed pretreated samples. The proposed new method provided statistically equivalent results to the standard washing method when an infrared balance was used for determining dry matter content in the controlled measurement experiment. Similarly, in the large historical data set, there was no statistical difference shown between the wash and no-wash methods. The new method is offered as an alternative method for determining the fraction of insoluble solids.     

Fermentation of “Quick Fiber” produced from a modified corn-milling process into ethanol and recovery of corn fiber oil

Approximately 9% of the 9.7 billion bushels of corn harvested in the United States was used for fuel ethanol production in 2002, half of which was prepared for fermentation by dry grinding. The University of Illinois has developed a modified dry grind process that allows recovery of the fiber fractions prior to fermentation. We report here on conversion of this fiber (Quick Fiber [QF]) to ethanol. QF was analyzed and found to contain 32%wt glucans and 65%wt total carbohydrates. QF was pretreated with dilute acid and converted into ethanol using either ethanologenic Escherichia coli strain FBR5 or Saccharomyces cerevisiae. For the bacterial fermentation the liquid fraction was fermented, and for the yeast fermentation both liquid and solids were fermented. For the bacterial fermentation, the final ethanol concentration was 30 g/L, a yield of 0.44 g ethanol/g of sugar(s) initially present in the hydrolysate, which is 85% of the theoretical yield. The ethanol yield with yeast was 0.096 gal/bu of processed corn assuming a QF yield of 3.04 lb/bu. The residuals from the fermentations were also evaluated as a source of corn fiber oil, which has value as a nutraceutical. Corn fiber oil yields were 8.28%wt for solids recovered following prtetreatment.     

Anticyanobacterial phenolic constituents from the aerial parts of Eupatorium fortunei Turcz

Four thymol derivatives and two phenolic compounds were isolated from the aerial parts of Eupatorium fortunei. The new structures were elucidated to be 7,8,9-trihydroxythymol (1), and 8,10-didehydro-7,9-dihydroxythymol (2) by means of MS and NMR analysis. The known compounds were identified as 8,9,10-trihydroxythymol (3), 10-acetoxy-8,9-dihydroxythymol (4), o-coumaric acid (5) and 4-(2-hydroxyethyl)benzaldehyde (6). Compound 3 showed strongest inhibitory effect on the growth of Microcystis aeruginosa in comparison with CuSO₄.