Modification of Anaerobic Digestion Model No. 1 for modeling anaerobic digestion of cattle manure with changing solids retention time.

In this study, Anaerobic Digestion Model No.1 (ADM1) was modified to incorporate changes in biochemical parameters due to solids retention time (SRT) variations. Cattle manure (CM) and thermally hydrolyzed CM were selected for testing. Continuous anaerobic digestion reactors were operated under different SRT conditions ranging from 6.6 to 36.0 days for both samples. The biochemical parameters (kch, kli, kpr, um,ac, um,bu, um,pro, um,va, Kac, Kbu, Kpro, and Kva) for each SRT condition were determined. To modify ADM1, the equations obtained through linear regression were substituted into biochemical parameters as a function of SRT. The modified ADM1 demonstrated superior accuracy compared with conventional ADM1. This study implies the feasibility of optimizing biochemical parameters for modeling in response to changes in environmental variables.

Feasibility of thermal hydrolysis pretreatment to reduce hydraulic retention time of anaerobic digestion of cattle manure.

In this study, we investigated the potential of thermal hydrolysis pretreatment (THP) to reduce the hydraulic retention times (HRTs) in the anaerobic digestion (AD) of cattle manure (CM). The AD with THP (THP AD) outperformed the control AD by over 1.4 times in terms of methane yield and volatile solid removal, even under the same HRT conditions. Remarkably, even when the THP AD was operated with an HRT of 13.2 d, it performed better than the control AD operated with an HRT of 36.0 d. In THP AD, there was a shift in the dominant archaeal genus responsible for methane generation from Methanogranum (at HRT of 36.0 - 13.2 d) to Methanosaeta (at HRT of 8.0 d). However, decreasing HRT, and applying THP resulted in reduced stability, accompanied by increased inhibitory compounds, and changes in the microbial community. Further confirmation is required to assess the long-term stability of THP AD.

Preoperative aspirin resistance does not increase myocardial injury during off-pump coronary artery bypass surgery.

We performed a prospective cohort trial on 220 patients undergoing elective off-pump coronary artery bypass surgery and taking aspirin to evaluate the effect of aspirin resistance on myocardial injury. The patients were divided into aspirin responders and aspirin non-responders by the value of the aspirin reaction units obtained preoperatively using the VerifyNow™ Aspirin Assay. The serum levels of troponin I were measured before surgery and 1, 6, 24, 48 and 72 hr after surgery. In-hospital major adverse cardiac and cerebrovascular events, graft occlusion, the postoperative blood loss and reexploration for bleeding were recorded. Of the 220 patients, 181 aspirin responders (82.3%) and 39 aspirin non-responders (17.7%) were defined. There were no significant differences in troponin I levels (ng/mL) between aspirin responders and aspirin non-responders: preoperative (0.04 ± 0.08 vs 0.03 ± 0.06; P = 0.56), postoperative 1 hr (0.72 ± 0.87 vs 0.86 ± 1.10; P = 0.54), 6 hr (2.92 ± 8.76 vs 1.50 ± 2.40; P = 0.94), 24 hr (4.16 ± 13.44 vs 1.25 ± 1.95; P = 0.52), 48 hr (2.15 ± 7.06 vs 0.65 ± 0.95; P = 0.64) and 72 hr (1.20 ± 4.63 vs 0.38 ± 0.56; P = 0.47). Moreover, no significant differences were observed with regard to in-hospital outcomes. In conclusion, preoperative aspirin resistance does not increase myocardial injury in patients undergoing off-pump coronary artery bypass surgery. Postoperative dual antiplatelet therapy might have protected aspirin resistant patients.