Objective: Photoacoustic tomography (PAT) is a rapidly evolving imaging modality that provides images with high contrast and spatial resolution showing the optical properties of biological tissues. The photoacoustic pressure is proportional to the product of the optical absorption coefficient and the local light fluence. The essential challenge in reconstructing quantitative images representing spatially varying absorption coefficients is the unknown light fluence. In addition, optical attenuation induces spatial variations in the light fluence, and the heterogeneity of the fluence determines the limits of reconstruction quality and depth. Approach: In this work, a reconstruction enhancement scheme is proposed to compensate for the variation of the light fluence in the absorption coefficient recovery. The inverse problem of the radiance Monte Carlo model describing light transport through the tissue is solved by using an alternating optimization strategy. In the iteration, the absorption coefficients and photon weights are alternately updated. Main results: The method provides highly accurate quantitative images of absorption coefficients in simulations, phantoms, and in vivo studies. The results show that the method has great potential for improving the accuracy of absorption coefficient recovery compared to conventional reconstruction methods that ignore light fluence variations. Comparison with state-of-the-art fluence compensation methods shows significant improvements in root mean square error, normalized mean square absolute distance, and structural similarity metrics. Significance: This method achieves high precision quantitative imaging by compensating for non-uniform light fluence without increasing the complexity and operation of the imaging system.

Anaerobic digestion (AD) has been considered as a promising technique for food waste (FW) recycling. However, the accumulation of volatile fatty acids (VFAs) restricts the stability of anaerobic reactors. The present study investigated the use of biochar produced at different conditions (750 °C-30 min, 750 °C-60 min, 750 °C-120 min, 550 °C-60 min, 650 °C-60 min, 850 °C-60 min, 950 °C-60 min) for enhancing the AD of FW. Batch experiments showed that all the biochar increased the methane production rates and biochar obtained at 750 °C-60 min resulted in the highest enhancement by 21.5%. It was further showed surface oxygen-containing functional groups and graphitization degree of biochar were the critical factors for improving methane production. Microbial analysis showed that biochar addition formed different microbial communities, and Methanosaeta, Romboutsia, and norank_f_Anaerolineaceae were enriched, which might be correlated with direct interspecies electron transfer (DIET). This research showed biochar could enhance the AD of FW and also revealed the main characteristics of biochar relating with the enhancement of AD. Graphical Abstract

No abstract

Long-chain fatty acids (LCFA) are difficult to be degraded in anaerobic digestion (AD), and the known LCFA degrading bacteria are only limited to the families Syntrophomonadaceae and Syntrophaceae . Here, we found that hydrochar effectively promoted AD of LCFA, and the new LCFA-degrading bacteria and a new metabolic pathway were also revealed based on genomic-centric metatranscriptomic analysis.

Southern blight caused by Sclerotium delphinii has devastating effect on Dendrobium catenatum (an extremely valuable medicinal and food homologous Orchidaceae plant). However, the mechanisms underlying S. delphinii infection and D. catenatum response is far from known. Here, we investigated the infection process and mode of S. delphinii by microscopic observations of detached leaves and living plantlets and further explored the hormonal and metabolomic responses of D. catenatum during S. delphinii infection by performing widely targeted metabolome method. The results showed that S. delphinii infection involves two stages: a contact phase (12–16 hours after inoculation) and a penetration stage (20 hours after inoculation). S. delphinii hyphae could penetrate leaves directly (via swollen hyphae and the formation of an infection cushion) or indirectly (via stomatal penetration), causing water-soaked lesions on leaves within 24–28 hours after inoculation and expanded thereafter. The content of jasmonates increased after the hyphal contact and remained at high levels during S. delphinii infection, while the ethylene precursor (1-Aminocyclopropanecarboxylic acid) accumulated significantly after penetration. Furthermore, metabolites of the phenylpropanoid and flavonoid pathways were enriched after pathogen penetration, while several amino acids accumulated in significant amount at the late stage of infection. Moreover, some other associated metabolites were significantly altered during pathogen infection. Therefore, the jasmonate, phenylpropanoid, flavonoid and amino acids pathways may play crucial roles in D. catenatum resistance to S. delphinii infection. This study provides insight into prevention and control of southern blight disease of D. catenatum.