Biomass is increasingly perceived as a renewable resource rather than as an organic solid waste today, as it can be converted to various chemicals, biofuels, and solid biochar using modern processes. In the past few years, pyrolysis has attracted growing interest as a promising versatile platform to convert biomass into valuable resources. However, an efficient and selective conversion process is still difficult to be realized due to the complex nature of biomass, which usually makes the products complicated. Furthermore, various contaminants and inorganic elements (e.g., heavy metals, nitrogen, phosphorus, sulfur, and chlorine) embodied in biomass may be transferred into pyrolysis products or released into the environment, arousing environmental pollution concerns. Understanding their behaviors in biomass pyrolysis is essential to optimizing the pyrolysis process for efficient resource recovery and less environmental pollution. However, there is no comprehensive review so far about the fates of chemical elements in biomass during its pyrolysis. Here, we provide a critical review about the fates of main chemical elements (C, H, O, N, P, Cl, S, and metals) in biomass during its pyrolysis. We overview the research advances about the emission, transformation, and distribution of elements in biomass pyrolysis, discuss the present challenges for resource-oriented conversion and pollution abatement, highlight the importance and significance of understanding the fate of elements during pyrolysis, and outlook the future development directions for process control. The review provides useful information for developing sustainable biomass pyrolysis processes with an improved efficiency and selectivity as well as minimized environmental impacts, and encourages more research efforts from the scientific communities of chemistry, the environment, and energy.

SUMMARY Invading viral DNA can be recognized by the host cytosolic DNA sensor, cyclic GMP-AMP (cGAMP) synthase (cGAS), resulting in production of the second messenger cGAMP, which directs the adaptor protein STING to stimulate production of type I interferons (IFNs). Although several DNA viruses are sensed by cGAS, viral strategies targeting cGAS are virtually unknown. We report here that Kaposi’s sarcoma-associated herpesvirus (KSHV) ORF52, an abundant gammaherpesvirus-specific tegument protein, subverts cytosolic DNA sensing by directly inhibiting cGAS enzymatic activity through a mechanism involving both cGAS- and DNA-binding. Moreover, ORF52 homologues in other gammaherpesviruses also inhibit cGAS activity and similarly bind cGAS and DNA, suggesting conserved inhibitory mechanisms. Furthermore, KSHV infection evokes cGAS-dependent responses that can limit the infection, and an ORF52-null mutant exhibits increased cGAS signaling. Our findings reveal a mechanism through which gammaherpesviruses antagonize host cGAS DNA sensing.

The interrelationship between alpha-synuclein (alpha-syn) and mitochondria is not clearly understood. Owing to the lack of the signal peptide and its predominant localization in the cytosol, alpha-syn is generally considered to affect mitochondrial function through some secondary effects. Contrary to this assumption, here, we show that a portion of alpha-syn is present in the membrane of mitochondria in normal dopaminergic neurons. The same profile is also found in other alpha-syn-positive neurons. Thus, binding to the membrane of mitochondria is the physiological nature of alpha-syn and might also contribute to the pathological role of this protein in the mitochondrial dysfunction in Parkinson's disease.

SARS-CoV-2 spike (S) mediates viral entry into cells and is critical for vaccine development against COVID-19. Structural studies have revealed distinct conformations of S, but real-time information that connects these structures, is lacking. Here we apply single-molecule Fluorescence (Förster) Resonance Energy Transfer (smFRET) imaging to observe conformational dynamics of S on virus particles. Virus-associated S dynamically samples at least four distinct conformational states. In response to human receptor Angiotensin-Converting Enzyme 2 (hACE2), S opens sequentially into the hACE2-bound S conformation through at least one on-path intermediate. Conformational preferences observed upon expsoure to convalescent plasma or antibodies suggest mechanisms of neutralization involving either competition with hACE2 for binding to the receptor-binding domain (RBD) or allosteric interference with conformational changes required for entry. Our findings inform on mechanisms of S recognition and conformations for immunogen design.

No abstract

BiOCl is known as a highly efficient photocatalyst for degradation of pollutants. However, effective methods for fabricating BiOCl nanomaterials with well-defined facets are still lacking. In this work, a facile synthetic method was developed for the fabrication of BiOCl nanodisks with exposed {001} facets. The central feature of this approach was the use of water as the hydrolysis agent and ethylene glycol as the crystal growth inhibitor agent to tune the growth of BiOCl nanomaterial. With this approach, the size and shape of BiOCl nanostructures could be effectively tuned through adjusting the volume ratio of ethylene glycol/H2O. In addition, the mechanism of the crystal growth in this fabrication process was elucidated. The as-prepared BiOCl nanodisks with exposed {001} facets exhibited an excellent photocatalytic activity towards Rhodamine B degradation under both ultraviolet and visible light irradiations. These findings shed light on the deep understanding of formation mechanisms of BiOCl nanodisks and provide an efficient and facile method for the synthesis of high active photocatalyst.

Many important gram-negative bacterial pathogens use highly sophisticated type III protein secretion systems (T3SSs) to establish complex host-pathogen interactions. Bacterial-host cell contact triggers the activation of the T3SS and the subsequent insertion of a translocon pore into the target cell membrane, which serves as a conduit for the passage of effector proteins. Therefore the initial interaction between T3SS-bearing bacteria and host cells is the critical step in the deployment of the protein secretion machine, yet this process remains poorly understood. Here, we use high-throughput cryo-electron tomography (cryo-ET) to visualize the T3SS-mediated Salmonella-host cell interface. Our analysis reveals the intact translocon at an unprecedented level of resolution, its deployment in the host cell membrane, and the establishment of an intimate association between the bacteria and the target cells, which is essential for effector translocation. Our studies provide critical data supporting the long postulated direct injection model for effector translocation.

SARS-CoV-2 spike (S) mediates entry into cells and is critical for vaccine development against COVID-19. S is synthesized as a precursor, processed into S1 and S2 by furin proteases, and activated for fusion when human angiotensin-converting enzyme 2 (hACE2) engages the receptor-binding domain (RBD) and when the N-terminus of S2 is proteolytically processed. Structures of soluble ectodomains and native virus particles have revealed distinct conformations of S, including a closed trimer with all RBD oriented downward, trimers with one or two RBDs up, and hACE2-stabilized conformations with up to three RBD oriented up. Real-time information that connects these structures, however, has been lacking. Here we apply single-molecule Forster Resonance Energy Transfer (smFRET) imaging to observe conformational dynamics of S on virus particles. Virus-associated S dynamically samples at least four distinct conformational states. In response to hACE2, S opens into the hACE2-bound S conformation through at least one on-path intermediate, with trypsin partially activating S. Conformational preferences of convalescent patient plasma and monoclonal antibodies suggest mechanisms of neutralization involving either direct competition with hACE2 for binding to RBD or allosteric interference with conformational changes required for entry. Our findings inform on mechanisms of S recognition and on conformations for immunogen design.