AD Process Research Articles

Biogas Produced by Anaerobic Digestion Process and Biodiesel from Date Seeds

Dates are an important food source in many countries that produce different types of dates. Dates have a significant amount of waste, either from planting or eating them. A large amount of seeds are produced from eating it. This study is considered to explore the quantity and the quality of biogas produced from the Sagai date seeds through the anaerobic digestion process (AD) before and after oil extraction and exploitation of oil in biodiesel production. In addition, the study aims to tests the resulted digestate from the AD process. This test was performed to ensure that the digestate contains the three basics elements (N, P and K) to be used in agriculture. In its preparation, the date seeds were ground after washing via a grinding machine without exposure to any other treatment process. Design of Experiments (DOE) was applied in determining the effect of temperature, volatile solid and sludge quantity on the resulted biogas. The energy balance at the optimum results was calculated. The highest biogas volumes from the AD of date seed before and after oil extraction were 4140 cc and 3534 cc, respectively, at 37 °C, 4.2 g-VS and 50% sludge quantity. While the highest methane/g-VS were 1143.8 cc/g-VS and 949.6 cc/g-VS, respectively, at 37 °C, 1.1 g-VS and 50% sludge quantity. The oil obtained using the Soxhlet method at 70 °C, 1:4 ratio of date seeds to n-hexane solvent and 5 h reaction time was 16% of the date seed mass (79% biodiesel and 9% glycerine). Therefore, the resultant effect from the main findings indicated that the study supports the investigation of the possibility of exploiting date seeds in the production of biogas, biodiesel and bio-fertiliser.

Ash-extracts from plant residues can provide sufficient buffering alkalinity and trace elements required to prevent operation instability to guarantee optimum methane yield during anaerobic digestion of agricultural residues

In this study, continuously stirred tank reactors (CSTR) operated at mesophilic temperatures were used to study the effectiveness of low-cost plant ash-extracts from plant residues in providing sufficient buffering alkalinity and trace elements required to prevent operational instability during an AD process to optimize methane productivity. The mean specific methane production (SMP) obtained from the unsupplemented CSTR was 79.3 N mL CH4/gVS fed, while supplemented reactors were 258.1 and 297.3 N mL CH4/gVS fed, respectively, corresponding to methane contents of 24.6 %, 56.7 % and 57.0 %, respectively. The unsupplemented CSTR failed when VFA accumulation occurred with acetic acid ranging between 2262–8917 mg/L, propionate-to-acetate (P: A) ratio 1:2.1–1:3.2 and a FOS: TAC ratio 0.2–1.4. Supplementation of the failed CSTR with ash-extracts increased the buffering potential of the reactors by decreasing VFA concentration leading to positive signs of recovery and a gradual increase in biogas production (p < 0.005). The soluble trace elements content in the ash-extracts and strong buffering alkalinity stabilized AD processes, improved SMP and facilitated the recovery of the failing CSTR. Thus, ash-extract supplements can increase the profitability of the AD process. The production and sale of ash can also support economic activities by creating a new business opportunity as the pathway to impact.

Carbon- and metal-based mediators modulate anaerobic methanogenesis and phenol removal: Focusing on stimulatory and inhibitory mechanism

In this study, anaerobic batch experiments were conducted to investigate the effect of carbon-based (biochar) and metal-based (nanoscale zero-valent iron, NZVI and zero valent iron, ZVI) mediators on the AD process treating phenolic wastewater. Fresh apricot shell- and wood-derived biochar (BiocharA, BiocharB) could remove the phenol efficiently (77.1% and 86.2%), suggesting that biodegradation cooperated with adsorption had advantage in phenol removal. BiocharB, NZVI and ZVI enhanced the methane production by 17.6%, 23.7% and 23.2%, respectively. Apart from serving as carrier for microbial growth, BiocharB might promote the direct interspecies electron transfer (DIET) since the Anaerolineaceae/Clostridium sensu stricto, which have potential for DIET, were enriched. NZVI and ZVI added systems mainly enhanced the abundance of Clostridium sensu stricto (24.5%, 37.6%) and Methanosaeta. Interestingly, BiocharA inhibited the methanogenesis completely. An inhibitory mechanism was proposed: the exposure of absorbed microbes on the BiocharA to the highly concentrated phenol in biochar’ pores resulted in the inhibition of methanogens, especially for Methanosarcina. In conclusion, this study showed that suitable biochar (BiocharB) could serve as an alternative redox mediator for realizing simultaneously the efficient phenol removal and methane production.

Improvement of biomethane potential of Elephant grass (Napier grass, Pennisetum purpureum Schum) by addition of biomass ash and ash-extracts as supplements

The effect of supplementing an AD process with biomass ash and ash-extracts was investigated in a 42-days BMP test using Elephant grass silage as feedstock. The results showed that the supplements increased BMP in the range between 314.6 and 359.6 N mL CH4/g VS fed. Buswell equation showed that the theoretical methane potential (TMP) of the grass was 491 N mL CH4/g VS fed and that the various treatments resulted in biodegradation rates ranging between 64.6 and 73.2%, corresponding to a 4–19% increase in the volume of methane produced. Also, hydrolysis constants from the first-order kinetic model ranged between 0.27 and 0.28 day−1. Gompertz model correctly predicted methane productivity and gave good fits (R2 > 0.97); lag time (λ) between 1.04 and 1.52 days from days 1 to 5. These results strongly suggest that the trace elements and alkalinity content of the ash extracts enhanced the degradation efficiency of Elephant grass and improved its methane yield.

Tau and TDP-43 synergy: a novel therapeutic target for sporadic late-onset Alzheimer\u2019s disease

Alzheimer’s disease (AD) is traditionally defined by the presence of two types of protein aggregates in the brain: amyloid plaques comprised of the protein amyloid-β (Aβ) and neurofibrillary tangles containing the protein tau. However, a large proportion (up to 57%) of AD patients also have TDP-43 aggregates present as an additional comorbid pathology. The presence of TDP-43 aggregates in AD correlates with hippocampal sclerosis, worse brain atrophy, more severe cognitive impairment, and more rapid cognitive decline. In patients with mixed Aβ, tau, and TDP-43 pathology, TDP-43 may interact with neurodegenerative processes in AD, worsening outcomes. While considerable progress has been made to characterize TDP-43 pathology in AD and late-onset dementia, there remains a critical need for mechanistic studies to understand underlying disease biology and develop therapeutic interventions. This perspectives article reviews the current understanding of these processes from autopsy cohort studies and model organism-based research, and proposes targeting neurotoxic synergies between tau and TDP-43 as a new therapeutic strategy for AD with comorbid TDP-43 pathology.

Co-anaerobic digestion of chicken manure with the addition of Cymbopogan citratus, Mentha piperita and Citrus sinensis as fly deterrent agents: Biogas production and Kinetic study

This paper describes the co-AD of chicken manure (CM) and the effect of additives such as serai wangi (SW), peppermint (PPM) and orange peel waste (OPW) on biogas production, kinetic study, and fly alleviation potential on the digestate. The results revealed that co-digestion of CM alone produced the highest biogas (62.43 mL/gvs) and methane yield (31.12 mL/gvs). OPW and PPM inhibit the AD process as they contain limonene, while high lignin content in SW slows down the overall AD process. Modified Gompertz and Cone model were applied to predict methane yield showed less than 10% error between measured and predicted methane yield. Modified Gompertz model is preferred as it shows a higher R2 value (0.962–0.999) and lower overall root mean square error (52.6%) compared to Cone model (0.953–0.999,63.27%). AD process alone could alleviate the fly issues as elimination of flies is shown towards the digestate due to low nitrogen content.

Comprehensive evaluation of different strategies to recover methanogenic performance in ammonia-stressed reactors

In this study, strategies for recovery of ammonia-stressed AD reactors were attempted, by addition of preserved bioaugmentation consortium in gel (BioG), fresh consortium in liquid medium (BioL), woodchip biochar (BW), and straw biochar (BS). In comparison to control group with ammonia, effective treatments, i.e., BioG, BioL, BW and BS raised the maximum methane production rate by 77%, 23%, 35%, and 24%, respectively. BW possibly acted as interspecies electrical conduits for Direct Electron Transfer based on conductivity and SEM analysis. BioG facilitated slow release of bioaugmentation inocula from gel into the AD system, which protected them from a direct environmental shock. According to microbial analysis, both BioG, BioL and BW resulted in increased relative abundance of Methanothermobacter thermautotrophicus; and BS induced selective raise of Methanosarcina thermophila. The increase of methanogens via these strategies led to the faster recovery of the AD process.

Effects of inhibitions by sodium ion and ammonia and different inocula on acetate-utilizing methanogenesis: Methanogenic activity and succession of methanogens

Acetate-fed anaerobic sequential batch experiments with four different inhibitory conditions (non-inhibitory (Lo), sodium-ion inhibitory (Na), ammonia inhibitory (Am), combined inhibitory (Hi)) were conducted using thirteen different inocula to investigate the inhibition effects by sodium-ion and ammonia and different inocula on acetate-utilizing methanogenesis and succession of methanogens. Sodium-ion and ammonia significantly extended lag-time λ and reduced specific-methanogenic-activity RCH4, and caused synergistic inhibition. The inhibition differed according to the initial methanogen community structures: the inhibition effects on λ and RCH4 were strongest ininocula with Methanosaeta concilii dominant and weakest in inocula with Methanoculleus bourgensis dominant. These inhibitory conditions determined the succession of methanogens: the most competitive methanogens were Methanosaeta concilii in Lo, Methanosarcina sp. in Na, Methanosarcina sp. and Methanoculleus bourgensis in Am, Methanoculleus bourgensis in Hi. This study provides valuable information for microbial management and optimization for AD processes treating wastewater that is rich in protein and/or salt.

Enhanced biomethanization of waste polylactic acid plastic by mild hydrothermal pretreatment: Taguchi orthogonal optimization and kinetics modeling

Polylactic acid (PLA) plastic is becoming a popular alternative to traditional petroleum-based plastics, but the biodegradability in engineered biological system is still a matter of concern. In this study, the biodegradability of PLA plastic at mesophilic and thermophilic AD were investigated, and a hydrothermal pretreatment was proposed to enhance the hydrolysis of PLA plastic and subsequent biomethanization. For raw PLA plastic, the biodegradation results indicated that PLA was hardly biodegraded at mesophilic conditions (only 50.5 ± 0.5 mL/g VS after 146 days). Although it was converted into biogas at thermophilic conditions after long incubation period (442.6 ± 1.1 mL/g VS), the long digestion time (T90 95.8 days) was destined to be infeasible for practical application. In contrast, hydrothermal pretreatment significantly enhanced the hydrolysis rates of PLA plastic in AD process from 0.001 day-1 for raw PLA plastic to 0.004–0.111 day−1. By balancing biogas production efficiency, energy and reagent cost, the conditions of 200 °C, 10 min and no alkali addition were recommended for hydrothermal pretreatment of waste PLA plastic in practice. At the optimized hydrothermal pretreatment conditions, 460.1 ± 25.0 mL/g VS was achieved in less than 30 days, which was comparable for AD of food waste (FW). Furthermore, LC-QEMS analysis proved that cleavages of ester bonds in PLA and its reaction with water molecule was the mechanism of triggering the hydrothermally decomposition of PLA. These results suggested the PLA-plastic waste co-mingled with OFMSW could be efficiently biomethanized into biogas by involving a mild hydrothermal pretreatment in practical application.

Improvement of solid-state anaerobic digestion of broiler farm-derived waste via fungal pretreatment

Fungus, Trichoderma longibrachiatum, was used for the pretreatment of broiler farm derived-lignocellulosic bedding material (rice husk) to enhance the subsequent solid-state anaerobic digestion (SS-AD). Fungal pretreatment efficacy was evaluated through a series of batch studies with respect to carbon-to-nitrogen (C/N) ratio and pretreatment time. Lignocellulosic outer layer structure disruption of the rice husk was prominent under the best fungal pretreatment condition evaluated (C/N ratio of 18.9 and pretreatment time of 7 days). Consequently, the resulting methane yield of 438.1 ± 20.0 NmL/gVSadded was obtained which was ~2.0-folds higher than that of the control (without pretreatment). Furthermore, in semi-continuous SS-AD, fungal pretreatment could significantly enhance digestibility of organic substance in high solid loading (30% total solids) AD process by 3.2-folds and improve microbial kinetic parameters with subsequent daily methane yield improvement by 2.4-folds. Thus, fungal pretreatment could be an environmentally-friendly and effective low-cost approach for broiler farm-derived waste management to enhance SS-AD efficacy.

In-app advertising: a two-step qualitative comparative analysis to explain clicking behavior

Purpose Individuals only click on a very small fraction of the in-app advertisements (ads) they are exposed to. Despite this fact, organizations spend generously placing in-app ads without theoretical knowledge of how the structure and the semantics of in-app ads influence individuals’ clicking behavior. This study aims to identify how the processing of structural and semantic factors leads to clicking behavior. Design/methodology/approach Based on the limited capacity theory, this paper proposes that the sequential processing of structural and semantic factors leads to clicking behavior. To mirror the sequential process, this paper applies a process-oriented configurational approach and performs a two-step qualitative comparative analysis (QCA) using 262 incidents of exposure to in-app ads. Findings The results support the proposed sequential processing and show that neither structural nor semantic factors alone lead to clicking behavior. This paper reveals four different paths of sequential processing of in-app ads that lead to clicking behavior. The results show that individuals click on non-animated in-app ads even though these are perceived as irritating or privacy-concerning. When the in-app ads are animated, individuals do only click on them when these are not irritating, privacy-concerning and personalized. Research limitations/implications Organizations can use these findings to improve their in-app ads and generate more clicks. This study recommends that organizations place in-app ads in a prominent location, design them similar to the design of the app and use bright colors. The advertising message needs to have new and relevant information in a credible and entertaining way. Depending on the degree of personalization, organizations should use different sizes of the in-app ad and only use animation if it is unlikely that the in-app ad caused irritation or privacy concerns. Practical implications Organizations can use these findings to improve their in-app ads and generate more clicks. This paper recommends that organizations place in-app ads in a prominent location, design them similar to the design of the app and with bright colors. The advertising message needs to have new and relevant information in a credible and entertaining way. Depending on the degree of personalization, organizations should use different sizes of the in-app ad and only use animation if it is unlikely that the in-app ad caused irritation or privacy concerns. Originality/value From the in-app ad perspective, this study is the first to theoretically develop and empirically show the sequential processing of structural and semantic factors of in-app ads. From the methodological perspective, this study applies an advanced configurational two-step QCA approach, which is capable of analyzing sequential processes and is new to marketing research.

Biochemical process evaluation of an anaerobic digester: a case study on long sustain commercial biogas plant

The anaerobic digestion technology has been established decades ago but still the commercial biogas industries are facing some challenges like process imbalance and failure of the digester, which has to be addressed by monitoring and identifying early warning indicators essential in the operation and maintenance. The aim of present study is to evaluate the early warning indicators during start-up: optimization, full load, and gradual overload phases of an 18-m3 commercial food waste biogas plant. The plant was operated by applying the optimal operation limits of FOS/TAC, TVFA/TA, IA/PA (Reply’s), and BA/TA ratios in the optimization of the AD process. The plant performance was studied in terms of methane yield, reduction in OLR, HRT, VS, and COD. The plant was operated for a span of 12 months at different OLRs ranging from 0.32 kg COD/m3/day (start-up) to 2.03 kg COD/m3/day (overload) in a mesophilic condition. Results showed that performance of AD at full load, in terms of biogas yield (m3/day) and methane yield (m3 CH4/(kg VS reduced) and m3 CH4/(kg COD reduced)), was found to be average of 32.65, 0.55, and 0.57, respectively. The process imbalance was observed from day 114 to day 119 of optimization period. The values of FOS/TAC, IA/PA, and TVFA/TA ratios were detected to be slightly more than the regular values, whereas bicarbonate alkalinity (BA) was abruptly reduced to 0.37 (kg CaCO3/m3). On the other hand, intermediate alkalinity (IA) value has been increased to 3.2 (kg CaCO3/m3), which was defined as limit for process instability. The gradual overload (0.6% more VS addition for 28 days) has no significant affect on the AD process and biogas production, but methane yield was slightly decreased.

Anaerobic co-digestion of fruit and vegetable waste: Synergy and process stability analysis

ABSTRACT Anaerobic mono- and co-digestion of fruits and vegetable waste (FVW), slaughterhouse waste (SHW), and cattle manure (CM) under mesophilic conditions (35°C) were conducted through biochemical methane potential tests to investigate how the FVW in a co-substrate formulation improves the methane yield, the degradative synergy between substrates, and especially the stability of the process. The co-digestion of FVW:SHW and FVW:CM were evaluated with volatile solids (VS) ratios of 1:2, 1:1, and 2:1. The results indicated that the highest synergistic effect was found in the co-digestion FVW:CM at 1:1 VS ratio. However, the co-digestion FWV:SHW at 1:2 VS ratio increased the methane yield by 74.2% compared to the mono-digestion of FVW (776.3 mL CH4 g VSadded −1). As a critical condition in these processes, the stability was evaluated using the early warning indicator VFA/TA (volatile fatty acids/total alkalinity). The co-substrate SHW promotes greater stability in methane production as the soluble carbohydrate content in FVW increases. It was proposed that the high protein (49.04 ± 0.96% VS) and ammonia content (693 ± 3 mg L−1) of SHW leads to the formation of a dampening system known as a carbonate-acetic buffer. It was concluded that balanced distribution between carbohydrates, proteins, and lipids is crucial to increase methane yields, and the low methane productions were associated with low N-NH4 + concentrations (FVW:CM co-digestions). The results obtained in this study can serve as a basis to design full-scale digesters under similar operating conditions and with the same substrate:co-substrate relationships. Implications: The production of methane from the anaerobic digestion process of food, and lose waste presents a viable alternative of valorization and could help to mitigate environmental impacts. However, anaerobic digestion from these substrates carries high instabilities and low methane yields. The need to increase these yields and contribute to process stability must be considered in the selection of a co-substrate. In this context, this work aims to evaluate the best fruits and vegetable waste: co-substrateformulation, that promotes higher methane yield, a synergy between substrates, and to improve the AD process stability in the presence of perturbations in the substrate composition. We believe that our results could be helpful for the design processes for methane production from fruit and vegetable waste, to contribute to competitiveness with conventional energies and promote the sustainability of these processes.

β-Amyloid and Lithium Affect the Magnitude of Phasic Dopamine Release in the Shell of the Nucleus Accumbens

Published data indicate that impairments to dopaminergic secretion in the shell of the nucleus accumbens play a role in the pathogenesis of Alzheimer’s disease (ad). The likely cause is an increase in the toxic form of β-amyloid in the brain. Like other pathogenetic processes in AD, this impairment may be mediated by an increase in glycogen synthase kinase 3 (GSK3) activity. The aim of the present work was to study the effect of β-amyloid on dopamine release in the shell of the nucleus accumbens. Changes in the dopamine level in the shell of the nucleus accumbens were recorded in vivo in 38 anesthetized male Wistar rats by fast scan cyclic voltammetry before and 1.5 h after experimental treatment. The ability of dopaminergic neurons to secrete dopamine was assessed in terms of the amplitude of responses to electrical stimulation of the ventral tegmental area (VTA). Neurotoxic processes typical of AD were modeled by giving β-amyloid (fragment 25–35) solution into the ventricular system of the brain. The role of GSK34 in mediating the effects of β-amyloid were evaluated by blocking the activity of this enzyme with an inhibitor, i.e., lithium. Lithium chloride solution at the “therapeutic” dose of 10.4 mg/kg was given i.p. immediately after β-amyloid injections. Increases in stimulated dopamine release provided evidence that during the 1.5 h after administration of both β-amyloid and lithium, the ability of ventral tegmental area neurons to secret dopamine in the shell of the nucleus accumbens was increased. Furthermore, comparison with the control group showed that these substances countered weakening of the secretory function induced by the experimental conditions. Lithium given simultaneously with β-amyloid weakened its action, evidencing involvement of GSK3 in this process.

Characterization of Aerosol Deposited Cesium Lead Tribromide Perovskite Films on Interdigited ITO Electrodes

AbstractAerosol deposition (AD) is a promising additive manufacturing method to fabricate low‐cost, scalable films at room temperature, but has not been considered for semiconductor processing, so far. The successful preparation of cesium lead tribromide (CsPbBr3) perovskite films on interdigitated indium tin oxide (ITO) electrodes by means of AD is reported here. The 20–35 µm thick layers are dense and have good adhesion to the substrate. The orthorhombic Pnma crystal structure of the precursor powder was retained during the deposition process with no signs of defect formation. The formation of electronic defects by photoluminescence spectroscopy is investigated and found slightly increased carrier recombination from defect sites for AD films compared to the powder. A nonuniform defect distribution across the layer, presumably induced by the impact of the semiconducting grains on the hard substrate surface, is revealed. The opto‐electronic properties of AD processed semiconducting films is further tested by electrical measurements and confirmed good semiconducting properties and high responsivity for the films. These results demonstrate that AD processing of metal halide perovskites is possible for opto‐electronic device manufacturing on 3D surfaces. It is believed that this work paves the way for the fabrication of previously unimaginable opto‐electronic devices by additive manufacturing.

The dynamics of theta-related pro-active control and response inhibition processes in AD(H)D

Impulsivity and deficits in response inhibition are hallmarks of attention-deficit(-hyperactivity) disorder (AD(H)D), can cause severe problems in daily functioning, and are thus of high clinical relevance. Traditionally, research to elucidate associated neural correlates has intensively, but also quite selectively examined mechanisms during response inhibition in various tasks. Doing so, in-between trial periods or periods prior to the response inhibition process, where no information relevant to inhibitory control is presented, have been neglected. Yet, these periods may nevertheless reveal relevant information. In the present study, using a case-control cross-sectional design, we take a more holistic approach, examining the inter-relation of pre-trial and within-trial periods in a Go/Nogo task with a focus on EEG theta band activity. Applying EEG beamforming methods, we show that the dynamics between pre-trial (pro-active) and within-trial (inhibition-related) control processes significantly differ between AD(H)D subtypes. We show that response inhibition, and differences between AD(H)D subtypes, exhibit distinct patterns of (at least) three factors: (i) strength of pre-trial (pro-active control) theta-band activity, (ii) the inter-relation of pro-active control and inhibition-relation theta band activity and (iii) the functional neuroanatomical region active during theta-related pro-active control processes. This multi-factorial pattern is captured by AD(H)D subtype clinical symptom clusters. The study provides a first hint that novel cognitive-neurophysiological facets of AD(H)D may be relevant to distinguish AD(H)D subtypes.

Biogas production from wastewater treatment: Evaluating anaerobic and biomagnetic systems

Biogas, a green and sustainable form of energy produced during the degradation of organic waste anaerobically comes with ecological and economic paybacks when compared to a comprehensive fossil fuel-based energy system. However, the biodiversity of microorganisms and chemical loads for enzymatic and bioconversion reactions impedes the anaerobic digester’s (AD) practicality for commercialization. Hence, this study examined the application of titanium dioxide magnetite (Fe-TiO2) (F) via a synthetic route in AD + F and a biomagnetic system (BMs) as a collective pathway to maximize methane potentials, wastewater treatment, and improve biogas production. The AD + F and BM systems were operated at a working volume of 0.8 L (inoculum to wastewater ratio of 0.6), the mesophilic temperature of 35 °C for an incubation period of 30 days. The results showed in-situ Fe-TiO2 facilitated the bio-electrolysis and bio-methanation reactions in the AD process which improved its performance as compared to the control (AD only). Above 75% of chemical oxygen demand (1600 ± 16.2 mg/L), Total Kjeldahl Nitrogen (76 ± 6.4 mg/L), total solids (135 ± 12 mg VS/L), volatile solids (94 ± 6.8 mg VS/L), and other inorganic contaminants (28 elementals) contained in the wastewater were removed by the BMs at a pH of 6.5 followed by the AD + F (65–75%) and the AD only (50–65%). On the 20th day, the control system (AD only) had a maximum daily biogas yield of 50 mL/COD.d, whereas the AD + F gave 90 mL/d and BMs 120 mL/d. Compared to the control with a methane yield of 66%, the addition of the Fe-TiO2 to AD + F and BMs increased the methane yield to 100%. Synergistically, the catalytic and biomagnetic activity of Fe-TiO2 in the BMs heightened the adsorption and reaction pathway of the contaminant’s transformations and degradation. Amidst two kinetic models investigated, the cumulative biogas yield followed the Gompertz kinetic model. In conclusion, combining the magnetic effect with green magnetic catalyst (Fe-TiO2) in AD and adsorption–based wastewater settings have viable prospects towards environmental purification.

Enhancement of Biogas Production from Co-Digestion of Industrial Solid Pineapple Wastes by Two-Stage Anaerobic Digestion Systems

This study aimed to investigate the biogas and methane production, as well as the COD removal efficiency by AD from pineapple solid wastes (PSW) as co-digestion feedstock. The two-stage of anaerobic digestion system was configured as continuously stirred tank reactor (CSTR) installed with anaerobic hybrid reactor (AHR) in order to enhance the efficiency and stability in biogas production. The PSW were firstly characterized for chemical composition. Then, the total solids (TS) were controlled as 4% of TS in influent loadings and four different HRTs were determined to investigate the subsequent effects, such as pH, total volatile acids and alkaline (TVA/Alk) ratio, biogas and methane production, and COD removal efficiency. The results demonstrated that the overall pH condition in CSTR was more acidic than AHR system and simultaneously performed in less stability of AD process by presence of massive TVA/Alk ratio. Furthermore, the maximum biogas production and COD removal efficiency were also observed in AHR system at 2,702 mL and 80.53% under HRT7 and HRT15, respectively. Interestingly, more than thousand millilitres of biogas production were dramatically increased from CSTR system under parallel operation. Thus, the separated acidogenic and methanogenic stage in two-stage system obviously improved the potential of AD process. However, the methane yields in AHR system remained stable in the range of 0.16-0.19m3/kgCOD removed, excepted at the lowest HRT condition (HRT5) by increasing OLRs. Thus, the optimal conditions for biogas production and COD removal could be varied, which depending on the types of feedstocks and operational reactors.

FMRI complexity is associated with tau‐PET and cognitive decline in Alzheimer’s disease

AbstractBackgroundAmyloid‐PET is considered an early marker for the preclinical stage of AD, while the neurofibrillary tangle pathology detected with tau‐PET imaging correlates more closely with neuronal injury and cognitive decline. However, PET scans are expensive and involve radiation exposure. Recently, entropy measures have been explored as indices of the complexity of rs‐fMRI time‐series. Reduced entropy values were associated with aging, APOE ɛ4 genotype and cognitive decline in AD. Here we use complexity of BOLD signals as an index of the information processing capacity of regional neuron populations, and test the hypothesis that it is sensitive to tau‐related neuronal injury and cognitive decline in the AD processes.MethodData used in this study were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Our cohort consisted of a sample of 50 subjects form ADNI‐3 (age = 72.4±8.2, 19M/31F, 25CN, 19MCI, 6AD) with a T1 structural, a tau‐PET (tracer: 18F‐AV1451) and two fMRI scans. FMRI data underwent standard preprocessing before computing Multi‐Scale Entropy (MSE). Parametric SUVR images were calculated with a cerebellar reference region. Correlations between SUVR tau‐PET and MSE were calculated for 195 ROIs (Craddock atlas parcellation) including age, gender and regional gray matter volume as covariates. To evaluate if MSE and PET can be used to classify AD from CN we trained and tested a random‐forest classifier (via 10‐fold cross‐validation).ResultWe found significant negative correlations between low frequency MSE and tau‐PET measures in hippocampus, parahippocampal gyrus and posterior cingulate cortex (Figure 2). The classification model revealed that MSE and PET have similar prediction accuracy and sensitivity (Table Figure 3A). The most informative areas for the prediction revealed a large degree of overlap between MSE and tau‐PET (Figure 3B).ConclusionCorrelation and classification results for MSE in relation with tau‐PET revealed areas in PCC, temporal and parietal lobes. These areas are implicated in tau pathology and cognitive decline. Hence, these overlapping findings support our hypothesis that the complexity of rs‐fMRI is associated with regional tau protein accumulation measured by PET and could provide a marker for information processing capacity of regional neuron populations and prediction of cognitive decline in the AD processes.

Brain network functional connectivity changes following psychosocial stress in subjective cognitive decline

AbstractBackgroundNeurodegenerative processes in early AD may disrupt the coordinated activity of brain networks important for the regulation of endocrine and emotional stress response. Stress reactivity and the effect of psychosocial stress on brain network function may thus be useful markers of neural changes related to early AD processes. The goal of this study was to examine the effect of psychosocial stress on brain network function in older adults with Subjective Cognitive Decline (SCD), a population at increased risk for Alzheimer’s disease.MethodParticipants (n=25) were evaluated to exclude cognitive impairment and significant psychiatric disorders. SCD was operationalized using the Cognitive Complaints Index (CCI) with a required minimum score of 20%.The Montreal Imaging Stress Task (MIST) was used to induce moderate psychosocial stress. Subjective measures included the stress subscale of the Stress‐Arousal Checklist (SACL) and the Profile of Mood States (POMS).Resting‐state fMRI scans were completed before and after the MIST. Seed‐based analyses were used to examine changes in functional connectivity (FC) in the default mode (DMN‐posterior cingulate), cognitive control (CCN‐dorsolateral prefrontal cortex), and salience (SN‐anterior insula) networks (p uncorrected &lt;0.005, FDR corrected p &lt;0.05).ResultParticipants had an average CCI of 45% (SD = 10.5%). There was an increase in subjective stress (stress‐SACL; t=6.12, p &lt; 0.0001) and worsening mood symptoms (POMS total score; t=3.23, p=0.004) during the MIST. In the DMN, stress exposure with the MIST resulted in decreased FC between the posterior cingulate cortex and regions of the CCN, (middle and superior frontal gyri). In the SN, stress exposure increased FC between the right anterior insula and the right middle/inferior temporal gyri and DMN regions including the precuneus and posterior cingulate cortex. We did not observe changes in FC in the CCN.ConclusionThese findings suggest that in SCD stress reduces coordinated activity of the CCN and DMN and increases connectivity between SN and DMN which may reflect impaired regulation of DMN activity and enhanced vigilance for emotional information. Further work is needed to determine how these changes may differ from normal aging and whether network changes may indicate early AD‐related cognitive and emotional disruption.