Hydrogen sulfide is a signaling molecule that regulates essential processes in plants, such as autophagy. In Arabidopsis (
), hydrogen sulfide negatively regulates autophagy independently of reactive ...oxygen species via an unknown mechanism. Comparative and quantitative proteomic analysis was used to detect abscisic acid-triggered persulfidation that reveals a main role in the control of autophagy mediated by the autophagy-related (ATG) Cys protease AtATG4a. This protease undergoes specific persulfidation of Cys170 that is a part of the characteristic catalytic Cys-His-Asp triad of Cys proteases. Regulation of the ATG4 activity by persulfidation was tested in a heterologous assay using the
CrATG8 protein as a substrate. Sulfide significantly and reversibly inactivates AtATG4a. The biological significance of the reversible inhibition of the ATG4 by sulfide is supported by the results obtained in Arabidopsis leaves under basal and autophagy-activating conditions. A significant increase in the overall ATG4 proteolytic activity in Arabidopsis was detected under nitrogen starvation and osmotic stress and can be inhibited by sulfide. Therefore, the data strongly suggest that the negative regulation of autophagy by sulfide is mediated by specific persulfidation of the ATG4 protease.
The aim of this paper was to analyze the biomethanization process of food waste (FW) from a university campus restaurant in six reactors with three different total solid percentages (20%, 25% and 30% ...TS) and two different inoculum percentages (20–30% of mesophilic sludge). The experimental procedure was programmed to select the initial performance parameters (total solid and inoculum contents) in a lab-reactor with V: 1100mL and, later, to validate the optimal parameters in a lab-scale batch reactor with V: 5000mL. The best performance for food waste biodegradation and methane generation was the reactor with 20% of total solid and 30% of inoculum: give rise to an acclimation stage with acidogenic/acetogenic activity between 20 and 60 days and methane yield of 0.49L CH4/g VS. Also, lab-scale batch reactor (V: 5000mL) exhibit the classical waste decomposition pattern and the process was completed with high values of methane yield (0.22L CH4/g VS). Finally, a protocol was proposed to enhance the start-up phase for dry thermophilic anaerobic digestion of food waste.
A hydrogen‐bonded cyclic tetramer is assembled with remarkably high effective molarities from a properly designed dinucleoside monomer. This self‐assembled species exhibits an impressive ...thermodynamic and kinetic stability and is formed with high fidelities within a broad concentration range.
Fine design of a dinucleoside monomer leads to hydrogen‐bonded macrocyclic tetramer assemblies with high effective molarities and remarkable thermodynamic and kinetic stability. The behavior of these assemblies in various solvents is discussed.
The influence of total solid contents during anaerobic mesophilic treatment of the organic fraction of municipal solid waste (MSW) has been studied in this work. The work was performed in batch ...reactors of 1.7
L capacity, during a period of 85–95 days. Two different organic substrate concentrations were studied: 931.1
mgDOC/L (20% TS) and 1423.4
mgDOC/L (30% TS). Experimental results showed that the reactor with 20% total solids content had significantly higher performance. Thus, the startup phase ended at 14 days and the total DOC removal was 67.53%. The startup in reactor R30 ended at 28 days obtaining 49.18% DOC removal. Also, the initial substrate concentration contributed substantially to the amount of methane in the biogas. Hence, the total methane production in the methanogenic phase was 7.01
L and 5.53
L at the end of the experiments for R20 and R30, respectively.
The effect of inoculum source on anaerobic thermophilic digestion of separately collected organic fraction of municipal solid wastes (SC_OFMSW) has been studied. Performance of laboratory scale ...reactors (V: 1.1 L) were evaluated using six different inoculums sources: (1) corn silage (CS); (2) restaurant waste digested mixed with rice hulls (RH_OFMSW); (3) cattle excrement (CATTLE); (4) swine excrement (SWINE); (5) digested sludge (SLUDGE); and (6) SWINE mixed with SLUDGE (1:1) (SWINE/SLUDGE). The SC_OFMSW was separately and collected from university restaurant. The selected conditions were: 25% of inoculum, 30% of total solid and 55
°C of temperature, optimum in the thermophilic range. The six inoculum sources showed an initial start-up phase in the range between 2 and 4
days and the initial methane generation began over 10
days operational process. Results indicated that SLUDGE is the best inoculum source for anaerobic thermophilic digestion of the treatment of organic fraction of municipal solid waste at dry conditions (30%
TS). Over 60
days operating period, it was confirmed that SLUDGE reactor can achieve 44.0%
COD removal efficiency and 43.0%
VS removal. In stabilization phase, SLUDGE reactor showed higher volumetric biogas generated of 78.9
mL/day (or 35.6
mL
CH
4/day) reaching a methane yield of 0.53
L
CH
4/g
VS. Also, SWINE/SLUDGE and SWINE were good inoculums at these experimental conditions.
The anaerobic mesophilic degradation of municipal waste has been studied in discontinuous lab-reactors with two different initial concentrations of OFMSW: R20, with 931.1
mg DOC/L (20% TS), and R30, ...with 1423.4
mg DOC/L (30% TS). The anaerobic digestion process was favoured when it was carried on material with a total solids content of 20% in comparison to a similar process with 30% TS. A higher level of organic matter, in terms of DOC and VFA, 18.18% and 8.09% respect, was removed in the system with the lower amount of solids. The kinetics parameters showed higher active biomass and a higher coefficient for the production of methane at the lower loading. The highest maximum specific growth rate for the microorganisms (
μ
MAX) in the reactors with 20% TS, a value of 0.192
d
−1, was achieved in comparison to 0.131
d
−1 in the reactors with 30% TS. The inverse of the F:M ratio was higher in the R20 system with a value of 0.0104 (cf. 0.0006 in R30) and, as a result, the R30 system required longer hydrolytic and acidogenic stages.
X
V
0
/
Y
X
/
S
and the yield coefficient for product generation (
α
P/S) were higher, by around 53%, for the R20 digester.
One of the major challenges in organic synthesis is the activation or deconstructive functionalization of unreactive C(sp3)–C(sp3) bonds, which requires using transition or precious metal catalysts. ...We present here an alternative: the deconstructive lactamization of piperidines without using transition metal catalysts. To this end, we use 3‐alkoxyamino‐2‐piperidones, which were prepared from piperidines through a dual C(sp3)–H oxidation, as transitory intermediates. Experimental and theoretical studies confirm that this unprecedented lactamization occurs in a tandem manner involving an oxidative deamination of 3‐alkoxyamino‐2‐piperidones to 3‐keto‐2‐piperidones, followed by a regioselective Baeyer–Villiger oxidation to give N‐carboxyanhydride intermediates, which finally undergo a spontaneous and concerted decarboxylative intramolecular translactamization.
Breaking down and building up: A new synthetic disconnection complementary to classical lactamization procedures is used to convert piperidines into pyrrolidinones in an unprecedented transition‐metal‐free reaction that can be conducted in one pot or in two steps. This selective oxidative ring contraction of N‐substituted piperidines should provide access to potentially bioactive compounds.
The influence of different organic fraction of municipal solid wastes during anaerobic thermophilic (55°C) treatment of organic matter was studied in this work: food waste (FW), organic fraction of ...municipal solid waste (OFMSW) and shredded OFMSW (SH_OFMSW). All digester operated at dry conditions (20% total solids content) and were inoculated with 30% (in volume) of mesophilic digested sludge. Experimental results showed important different behaviours patterns in these wastes related with the organic matter biodegradation and biogas and methane production. The FW reactor showed the smallest waste biodegradation (32.4% VS removal) with high methane production (0.18 LCH4/gVS); in contrast the SH_OFMSW showed higher waste biodegradation (73.7% VS removal) with small methane production (0.05 LCH4/g VS). Finally, OFMSW showed the highest VS removal (79.5%) and the methane yield reached 0.08 LCH4/g VS. Therefore, the nature of organic substrate has an important influence on the biodegradation process and methane yield. Pre-treatment of waste is not necessary for OFMSW.
•Kinetic conditions have been compared in dry anaerobic digestion of complex wastes.•The condition evaluated has been the temperature, exactly, mesophilic (35°C) and thermophilic (55°C) ...range.•Important kinetic differences are showed between both processes, even though of complex wastes.•The conclusions may help to increase the efficiency in dry anaerobic process at industrial scale.
Temperature is a significant variable in anaerobic digestion (AD) since it determines the values of the main kinetic parameters for the process and, hence, the rate of the microbiological process. Thus, in this study, batch AD experiments were carried out, at mesophilic (35°C) and thermophilic (55°C) conditions, with the aim to compare the kinetic of both processes. Tests were performed in dry conditions (concentration of Total Solids (TSs) of 20%) using the Organic Fraction of Municipal Solid Waste (OFMSW) as feedstock.
Romero model 1 was used to fit the experimental results from both, the organic matter consumption and the biogas production. This model has been used extensively in the analysis of results of AD process in a wide range of experimental conditions 2–4.
The values of the maximum specific growth rate of microorganisms (μMAX) are 27–60% higher for thermophilic process than for mesophilic ones and, therefore, the same level of organic matter degradation and methane production can be achieved in a shorter operating time, 20days in thermophilic instead of 40days in mesophilic. Moreover, the yield coefficient for methane production (αP/S) and the initial amount of active microorganisms (XV0/YX/S) show values 107% and 129% higher, respectively, in thermophilic processes.
Aim
This observational cohort study aimed: (i) to determine retrospectively after a 1‐ to 12‐year follow‐up period, the strength and independence of the association of various patient‐, tooth‐ and ...treatment‐related prognostic variables with the outcome of root canal treatment in patients with pre‐therapeutic apical periodontitis; and (ii) to establish the concordance between those predictors evaluated by both cone‐beam computed tomography (CBCT) and digital periapical radiography (DPR).
Methodology
The study cohort included 125 teeth in 84 individuals. The postoperative clinical signs/symptoms, plus DPR/CBCT‐PAI estimations, were used to determine the healing outcome. For statistical analysis, results were dichotomized into completely healed periapical structures versus persistent disease cases. The association between candidate predictor variables with persistent disease was analysed individually and adjusted for confounders using a multivariate binary logistic regression model.
Results
The success rate was 53.6%. After logistic regression analysis, mandibular tooth location, periapical lesion size >10 mm, poor quality of the coronal restoration, lack of magnification/illumination, lack of disinfection of gutta‐percha, time elapsed to definitive coronal restoration >1 week and poor density of root canal filling remained as robust predictors of failures. Concordance between DPR and CBCT scores varied from moderate to almost perfect agreement.
Conclusions
The findings of this study suggest that several tooth‐ and treatment‐related predictor variables, including tooth location, periapical radiolucency size, quality of the coronal restoration, magnification/illumination, disinfection of gutta‐percha, time elapsed to definitive coronal restoration, as well as, the density of root canal filling may act strongly and independently for determining the root canal treatment outcome in teeth with pre‐therapeutic apical periodontitis.
PDF
