ABSTRACT
Acrylic pressure sensitive adhesives, modified by polyurethane (PU), achieve selective optimization through the designability of polyurethanes. In this paper, PU macromonomers were prepared by a two-step synthesis method, using polypropylene glycol or polyethylene glycol with different molecular weights as soft segments and different types of diisocyanates: isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethylmethane diisocyanate (HMDI), 2,4-toluene diisocyanate (TDI), and 4,4'-diphenylmethane diisocyanate (MDI) and chain extenders as hard segments. After being terminated by capping agents, a series of PU macromonomers of different molecular weights and structures were obtained and used to modify the acrylic base adhesives. Compared to unmodified adhesives, acrylic adhesives modified by PU macromonomers have improved adhesion performances and heat resistance and show an increasing trend with the increase of molecular weight of diols. Diols with a molecular weight of 600 have the best effect. Diisocyanates containing benzene rings can better improve the thermal performance of adhesives, where P MDI containing a biphenyl ring is the best, while aliphatic isocyanate groups have a greater improvement in adhesion performance, and the adhesion performance of P HDI with a long carbon chain is the best.
ABSTRACT
Phomactin diterpenoids possess a unique bicyclo[9.3.1]pentadecane skeleton with multiple oxidative modifications, and are good platelet-activating factor (PAF) antagonists that can inhibit PAF-induced platelet aggregation. In this study, we identified the gene cluster (phm) responsible for the biosynthesis of phomactins from a marine fungus, Phoma sp. ATCC 74077. Despite the complexity of their structures, phomactin biosynthesis only requires two enzymes: a type I diterpene cyclase PhmA and a P450 monooxygenase PhmC. PhmA was found to catalyze the formation of the phomactatriene, while PhmC sequentially catalyzes the oxidation of multiple sites, leading to the generation of structurally diverse phomactins. The rearrangement mechanism of the diterpene scaffold was investigated through isotope labeling experiments. Additionally, we obtained the crystal complex of PhmA with its substrate analogue FGGPP and elucidated the novel metal-ion-binding mode and enzymatic mechanism of PhmA through site-directed mutagenesis. This study provides the first insight into the biosynthesis of phomactins, laying the foundation for the efficient production of phomactin natural products using synthetic biology approaches.
Subject(s)
Diterpenes , Platelet Activating Factor , FungiABSTRACT
Flavoprotein monooxygenases (FPMOs) play important roles in generating structural complexity and diversity in natural products biosynthesized by typeâ II polyketide synthases (PKSs). In this study, we used genome mining to discover novel mutaxanthene analogues and investigated the biosynthesis of these aromatic polyketides and their unusual xanthene framework. We determined the complete biosynthetic pathway of mutaxathene through in vivo gene deletion and in vitro biochemical experiments. We show that a multifunctional FPMO, MtxO4, catalyzes ring rearrangement and generates the required xanthene ring through a multistep transformation. In addition, we successfully obtained all necessary enzymes for in vitro reconstitution and completed the total biosynthesis of mutaxanthene in a stepwise manner. Our results revealed the formation of a rare xanthene ring in typeâ II polyketide biosynthesis, and demonstrate the potential of using total biosynthesis for the discovery of natural products synthesized by typeâ II PKSs.
Subject(s)
Biological Products , Polyketides , Polyketide Synthases/metabolism , Mixed Function Oxygenases/genetics , Mixed Function Oxygenases/metabolism , Polyketides/chemistry , Secondary Metabolism , Biological Products/chemistryABSTRACT
A novel actinobacterium with antimicrobial activity, designated strain H16431T, was isolated from a sediment sample collected from Dianchi Lake, Yunnan Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain H16431T was most closely related to Nonomuraea rhizosphaerae CGMCC 4.7431T and Nonomuraea guangzhouensis CGMCC 4.7101T (98.1% similarity), but formed a monophyletic clade with Nonomuraea ceibae KCTC 39826T (98.0% similarity). Phylogenomic analysis based on whole-genome sequence showed that strain H16431T formed a separate clade within the genus Nonomuraea. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values between strain H16431T and its closely related Nonomuraea species were 80.0-81.5%, 71.2-74.6%, and 23.2-25.0%, respectively, which were significantly lower than the widely accepted species-defined threshold. The DNA G + C content was 70.2% based on the whole-genome sequence. The menaquinones were identified as MK-9(H4), MK-9(H6), and MK-9(H2). The major fatty acids were iso-C16:0, 10 methyl-C17:0, and iso-C16:0 2OH. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, and phosphatidylinositol. These chemotaxonomic characteristics were corresponded to those of the genus Nonomuraea. On the basis of the taxonomic evidence, strain H16431T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea sediminis sp. nov. is proposed. The type strain is H16431T (=JCM 34852T=CICC 25119T).
Subject(s)
Actinomycetales , Anti-Infective Agents , Phosphatidylethanolamines , Phylogeny , RNA, Ribosomal, 16S/genetics , Lakes , DNA, Bacterial/genetics , China , Bacterial Typing Techniques , Sequence Analysis, DNA , Soil Microbiology , Diaminopimelic Acid/chemistry , Actinomycetales/genetics , Phospholipids/chemistry , Fatty Acids/chemistry , Vitamin K 2/chemistryABSTRACT
In recent years, terahertz waves have attracted significant attention for their promising applications. Due to a broadband optical response, an ultra-fast relaxation time, a high nonlinear coefficient of graphene, and the flexible and controllable physical characteristics of its meta-structure, graphene metamaterial has been widely explored in interdisciplinary frontier research, especially in the technologically important terahertz (THz) frequency range. Here, graphene's linear and nonlinear properties and typical applications of graphene metamaterial are reviewed. Specifically, the discussion focuses on applications in optically and electrically actuated terahertz amplitude, phase, and harmonic generation. The review concludes with a brief examination of potential prospects and trends in graphene metamaterial.
ABSTRACT
A PNP-pincer ligand provides a versatile ligation framework, which is highly useful in organometallic chemistry and catalytic chemistry. In this work, by a de novo strategy, a simple and efficient synthetic pathway, has been developed to prepare the new iminodibenzyl-based PNP pincer proligand imin-RPNP(Li or H) (R = isopropyl, phenyl). By employing salt metathesis or direct alkyl elimination, we successfully synthesized a series of iminodibenzyl-PNP rare-earth-metal (Ln = Sc, Y, Dy, Ho, Er, Tm, Lu) complexes and characterized them by NMR and X-ray diffraction analyses. Upon addition of a borate and triisobutylaluminum (TIBA), the rare-earth-metal complexes 2-Y, 2-Dy, 2-Ho, 2-Er, and 2-Tm bearing the imin-PhPNP ligand exhibited unexpectedly high 3,4-selectivity (up to 95%) for the polymerization of 1,3-dienes (isoprene and myrcene); in particular, the chosen yttrium complex 2-Y promoted the 1,3-diene polymerization in a living manner. A computational study suggested that the sterically congested configuration around the metal center imposed by the imin-RPNP ligand might be the main reason for this unusual selectivity.
ABSTRACT
Predicting a victim's stature from a dismembered body or human remains is a challenge in forensic practice. Lower extremity dimensions, such as the foot, are essential measurements for stature estimation. However, there is no available information on stature prediction generated from Taiwanese female foot measurements in the forensic science field. Hence, this study aims to investigate the correlations between various foot dimensions and stature and develop population-specific stature-prediction equations for Taiwanese females. Bilateral data of 12 foot dimensions were collected from 1058 females aged from 18 to 59 years using three-dimensional scanning. A pairedt-test is performed to evaluate bilateral differences, and linear and stepwise regression analyses are performed to generate stature predictions. The results indicate significant bilateral differences in the majority of the foot measurements. All measurements are positively correlated with stature (p < .05). Higher correlation coefficients with stature are observed in length-related foot dimensions, followed by girth- and breadth-related dimensions. The foot length on both sides is selected as an accurate and reliable parameter to conduct linear stature-predicting regression for Taiwanese females because it exhibits the highest explanation rate (right: 54.1%; left: 50.8%) and lowest estimating standard error (right: 3.883 cm, left: 4.020 cm) among the 12 foot measurements. Based on the results of the stepwise regression analysis, several stature-prediction equations consisting of various foot measurements are established. The findings of this study can provide helpful information for predicting the stature of Taiwanese females from fragmentary foot remains.
Subject(s)
Body Height , Forensic Anthropology , Female , Foot/anatomy & histology , Humans , Linear Models , Regression AnalysisABSTRACT
Plant exosome-like nanovesicles, being innately replete with bioactive lipids, proteins, RNA, and other pharmacologically active molecules, offer unique morphological and compositional characteristics as natural nanocarriers. Furthermore, their compelling physicochemical traits underpin their modulative role in physiological processes, all of which have fostered the concept that these nanovesicles may be highly proficient in the development of next-generation biotherapeutic and drug delivery nanoplatforms to meet the ever-stringent demands of current clinical challenges. This review systemically deals with various facets of plant exosome-like nanovesicles ranging from their origin and isolation to identification of morphological composition, biological functions, and cargo-loading mechanisms. Efforts are made to encompass their biotherapeutic roles by elucidating their immunological modulating, anti-tumor, regenerative, and anti-inflammatory roles. We also shed light on re-engineering these nanovesicles into robust, innocuous, and non-immunogenic nanovectors for drug delivery through multiple stringent biological hindrances to various targeted organs such as intestine and brain. Finally, recent advances centered around plant exosome-like nanovesicles along with new insights into transdermal, transmembrane and targeting mechanisms of these vesicles are also elucidated. We expect that the continuing development of plant exosome-like nanovesicle-based therapeutic and delivery nanoplatforms will promote their clinical applications.
Subject(s)
Exosomes/metabolism , Extracellular Vesicles/metabolism , Nanoparticles , Plant Cells/metabolism , Drug Carriers , Drug Delivery Systems , Humans , Theranostic NanomedicineABSTRACT
In order to improve the practicality of the rapid biochemical oxygen demand (BOD) method, a highly sensitive rapid detection method for BOD that is based on establishing the correlation between current and dissolved oxygen (DO) was developed. In this experiment, Bacillus subtilis was used as the test microorganism, and the embedding method was used to achieve quantitative fixation of microorganisms, which could increase the content of microorganisms and prolong the service life of the biological element. The conductivity (COND) probe is used as a sensing element, so that the testing value can be read every second. In the program, the moving average method is used to process the collected data so that the value can be read every minute. National standard samples were detected to test the accuracy and stability of the method. The results showed that relative error and analytical standard deviations were less than 5%. Different polluted water was tested to evaluate its application range. The results showed that relative error was less than 5%. The results of the method are consistent with the results of the wastewater sample obtained by the BOD5 standard method. The proposed rapid BOD current sensing biosensor method should be promising in practical application of wastewater monitoring.
Subject(s)
Biological Oxygen Demand Analysis/methods , Biosensing Techniques/methods , Oxygen/chemistry , Wastewater/chemistryABSTRACT
Collision warning system plays a key role in the prevention of driving distractions and drowsy driving. Previous studies have proven the advantages of tactile warnings in reducing driver's brake response time. At the same time, tactile warnings have been proved effective in take-over request (TOR) for partially autonomous vehicles. How the performance of tactile warnings can be optimized is an ongoing hot research topic in this field. Thus, the presented low-cost driving simulation software and methods are introduced to attract more researchers to take part in the investigation. The presented protocol has been divided into five sections: 1) participants, 2) driving simulation software configuration, 3) driving simulator preparation, 4) vibrating toolkit configuration and preparation, and 5) conducting the experiment. In the exemplar study, participants wore the tactile vibrating toolkit and performed an established car-following task using the customized driving simulation software. The front vehicle braked intermittently, and vibrating warnings were delivered whenever the front vehicle was braking. Participants were instructed to respond as quickly as possible to the sudden brakes of the front vehicle. Driving dynamics, such as the brake response time and brake response rate, were recorded by the simulation software for data analysis. The presented protocol offers insight into the exploration of the effectiveness of tactile warnings on different body locations. In addition to the car-following task that is demonstrated in the exemplar experiment, this protocol also provides options to apply other paradigms to the driving simulation studies by making simple software configuration without any code development. However, it is important to note that due to its affordable price, the driving simulation software and hardware introduced here may not be able to fully compete with other high-fidelity commercial driving simulators. Nevertheless, this protocol can act as an affordable and user-friendly alternative to the general high-fidelity commercial driving simulators.
Subject(s)
Automobile Driving , Computer Simulation , Research , Touch/physiology , Vibration , Accidents, Traffic/prevention & control , Data Analysis , Female , Humans , Male , Reaction Time/physiology , Software , Task Performance and Analysis , Wearable Electronic Devices , Young AdultABSTRACT
Marine-derived fungi are a rich source of structurally diverse metabolites. Fungi produce an array of compounds when grown under different cultivation conditions. In the present work, different media were used to cultivate the fungus Aspergillus sp. ZA-01, which was previously studied for the production of bioactive compounds, and three new prenylxanthone derivatives, aspergixanthones Iâ»K (1â»3), and four known analogues (4â»7) were obtained. The absolute configuration of 1 was assigned by ECD experiment and the Mo2(AcO)4 ICD spectrum of its methanolysis derivative (1a). All the compounds (1â»7) were evaluated for their anti-Vibrio activities. Aspergixanthone I (1) showed the strongest anti-Vibrio activity against Vibrio parahemolyticus (MIC = 1.56 µM), Vibrio anguillarum (MIC = 1.56 µM), and Vibrio alginolyticus (MIC = 3.12 µM).
Subject(s)
Anti-Bacterial Agents/pharmacology , Aquatic Organisms/metabolism , Aspergillus/metabolism , Vibrio/drug effects , Xanthones/pharmacology , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/metabolism , Drug Evaluation, Preclinical , Microbial Sensitivity Tests , Molecular Structure , Proton Magnetic Resonance Spectroscopy , Xanthones/isolation & purification , Xanthones/metabolismABSTRACT
Development of bifunctional non-metal electrocatalyst for oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) with high efficiency, durable stability and low cost is a crucial and challenging issue. However, the heteroatom-doped carbon material including a carbon-based conductive additive would be easily oxidized under the high potential needed for driving the OER. Besides, the interaction between the heteroatom-doped carbon material that possesses electrocatalyst activity and a carbon-based conductive additive is weak, affecting the performance of the electrocatalyst. In this context, we introduce CoS nanoparticles into a three-dimensional N-doped carbon framework (CoS/NCF) by a morphology-retaining pyrolysis of polyaniline/CoS framework precursor, in which the polyaniline framework provides abundant functional groups to nucleate and grow CoS nanoparticles while retaining its interconnected three-dimensional porous structure. Benefiting from (i) the lower OER potential of CoS nanoparticles than the electro-oxidation decomposition potential of a carbon material and (ii) the strong affinity of CoS nanoparticles for a N-doped carbon framework, higher stability than commercial Pt/C system and greater catalytic activity towards ORR with an onset potential of about 0.921 V versus reversible hydrogen electrode (RHE) are observed. Furthermore, only a potential of 1.515 V versus RHE is required for achieving a current density of 10 mA cm-2.
ABSTRACT
Determination of the absolute configrations for natural products is one of the most important and challenging tasks, especially when the molecules display high conformational flexibility. In this paper, eight new prenylxanthones, aspergixanthones A-H (1-8), and one known analogue (9), were isolated from the marine-derived fungus Aspergillus sp. ZA-01. The absolute configurations of C-14 and C-15 in 1-8 were difficult to be assigned due to the high conformational flexibility of the chains. To solve this problem, the experimental ECD, ORD, and VCD spectra of 1 were combined for analysis with the corresponding theoretical predictions for its different diastereomers. This study suggested that a concerted application of more than one chiroptical methods could be used as a preferable approach for the stereochemical characterizations of flexible molecules. Compounds 1-9 were evaluated for their cytotoxic and antibacterial activities. Among them, 6 showed cytotoxicity against the A-549 cell line with the IC50 value of 1.1 µM, and 7 exhibited antibacterial activity against Micrococcus lysodeikticus with the MIC value of 0.78 µg/mL.
Subject(s)
Aquatic Organisms/chemistry , Aspergillus/chemistry , Biological Products/chemistry , Molecular Conformation , Xanthones/chemistry , A549 Cells , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacology , Biological Products/isolation & purification , Biological Products/pharmacology , Drug Screening Assays, Antitumor , Humans , Inhibitory Concentration 50 , Microbial Sensitivity Tests , Micrococcus/drug effects , Stereoisomerism , Xanthones/isolation & purification , Xanthones/pharmacologyABSTRACT
BACKGROUND: Long-term persistence of statin therapy provided an ongoing reduction in mortality among patients with and without a known history of CVD, and renoprotective effect on CKD patients. Until now, very few reports are available from China to address the effects of statin therapy in CKD + CAD patients. METHODS: We compared the effects of long-term statin therapy (follow-up time 4 years) in terms of cardiovascular events, all-cause death, and cardiac death among 254 CKD patients with or without CAD. RESULTS: Long-term statin therapy was much more effective in the CKD + CAD patients compared with CKD patients. In the CAD + CKD patients, long-term statins showed a 22.2% reduction in the CVs rate (P = 0.012). With regard to the all-cause and cardiac deaths, long-term statins had significant treatment effects on the CAD + CKD patients (reduction of about 28.1% in mortality rates, P < 0.001). In contrast, long-term statin therapy exerted no significant influence on the clinical outcomes of the CKD-only patients. CONCLUSION: Long-term statin therapy more dramatically reduced the CVs and mortality rates of the CKD patients with concomitant CAD. In contrast, CKD-only patients had a good prognosis and did not appear to require statin treatment.
Subject(s)
Coronary Artery Disease/complications , Coronary Artery Disease/drug therapy , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Renal Insufficiency, Chronic/complications , Renal Insufficiency, Chronic/drug therapy , Female , Humans , Kaplan-Meier Estimate , Male , Proportional Hazards Models , Treatment OutcomeABSTRACT
Metformin (Met) is a widely used antidiabetic drug and has demonstrated interesting anticancer effects in various cancer models, alone or in combination with chemotherapeutic drugs. The aim of the present study is to investigate the synergistic effect of Met with cisplatin (Cis) on the tumor growth inhibition of gallbladder cancer cells (GBC-SD and SGC-996) and explore the underlying mechanism. Cells were treated with Met and/or Cis and subjected to cell viability, colony formation, apoptosis, cell cycle, western blotting, xenograft tumorigenicity assay and immunohistochemistry. The results demonstrated that Met and Cis inhibited the proliferation of gallbladder cancer cells, and combination treatment with Met and Cis resulted in a combination index < 1, indicating a synergistic effect. Co-treatment with Met and Cis caused G0/G1 phase arrest by upregulating P21, P27 and downregulating CyclinD1, and induced apoptosis through decreasing the expression of p-PI3K, p-AKT, and p-ERK. In addition, pretreatment with a specific AKT activator (IGF-1) significantly neutralized the pro-apoptotic activity of Met + Cis, suggesting the key role of AKT in this process. More importantly, in nude mice model, Met and Cis in combination displayed more efficient inhibition of tumor weight and volume in the SGC-996 xenograft mouse model than Met or Cis alone. Immunohistochemistry analysis suggests the combinations greatly suppressed tumor proliferation, which is consistent with our in vitro results. In conclusion, our findings indicate that the combination therapy with Met and Cis exerted synergistic antitumor effects in gallbladder cancer cells through PI3K/AKT/ERK pathway, and combination treatment with Met and Cis would be a promising therapeutic strategy for gallbladder cancer patients.
ABSTRACT
Six new azaphilone derivatives, talaraculones A-F (1-6), together with five known analogues (7-11), were obtained from the saline soil-derived fungus Talaromyces aculeatus. The absolute configurations of 1 and 6 were assigned by quantum chemical calculations of the electronic circular dichroism (ECD) spectra. Compounds 1 and 5 represent the first reported azaphilone derivatives with a C4 aliphatic side chain and a methylal group at C-3, respectively. Talaraculones A and B (1 and 2) exhibited stronger inhibitory activity against α-glucosidase than the positive control acarbose (IC50 = 101.5 µM), with IC50 values of 78.6 and 22.9 µM, respectively.
Subject(s)
Acarbose/chemistry , Benzopyrans/isolation & purification , Benzopyrans/pharmacology , Pigments, Biological/isolation & purification , Pigments, Biological/pharmacology , Talaromyces/chemistry , alpha-Glucosidases/chemistry , Benzopyrans/chemistry , Circular Dichroism , Inhibitory Concentration 50 , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Pigments, Biological/chemistry , alpha-Glucosidases/metabolismABSTRACT
BACKGROUND: Osteoporotic vertebral compression fractures (OVCFs) constitute an age-related health problem that affects approximately 200 million people worldwide. Currently, various treatments are performed with the goal of reducing pain, stabilizing the vertebrate, and restoring mobility. In this study, we aimed to assess the efficacy and safety of vertebroplasty (VP), kyphoplasty (KP), and conservative treatment (CT) for the treatment of OVCFs. METHODS: We performed a network meta-analysis. PubMed and Embase databases were searched to identify randomized controlled trials (RCTs) that contained at least one of the following outcomes: visual analog scale (VAS), Roland-Morris Disability Questionnaire (RDQ), European Quality of Life-5 Dimensions (EQ-5D), and new fractures. Odds ratios with 95% confidence intervals (CIs) were used to calculate the risk of new fractures, and mean differences (MDs) with 95% CIs were utilized to express RDQ, EQ-5D, and VAS outcomes. RESULTS: Sixteen RCTs with 2046 participants were included in this meta-analysis. Compared with CT, patients treated with VP had improved pain relief, daily function, and quality of life; however, no significant differences were found between VP and KP for these 3 outcomes. All treatment options were associated with comparable risk of new fractures. When the rank probability was assessed to distinguish subtle differences between the treatments, VP was the most effective treatment for pain relief, followed by KP and CT; conversely, KP was the most effective in improving daily function and quality of life and decreasing the incidence of new fractures, followed by VP and CT. CONCLUSION: VP might be the best option when pain relief is the principle aim of therapy, but KP was associated with the lowest risk of new fractures and might offer better outcomes in terms of daily function and quality of life.
Subject(s)
Conservative Treatment , Fractures, Compression/therapy , Kyphoplasty , Osteoporotic Fractures/therapy , Spinal Fractures/therapy , Vertebroplasty , Conservative Treatment/adverse effects , Humans , Kyphoplasty/adverse effects , Network Meta-Analysis , Vertebroplasty/adverse effectsABSTRACT
BACKGROUND: Cardiovascular disease (CVD) is often comorbid with chronic kidney disease (CKD). Small low-density lipoprotein cholesterol (sdLDL-C) has also been found to increase risk for CVD. The goal of the present study was to determine the nature of the relationship between sdLDL-C concentration and CVD in patients with CKD. METHODS: One-hundred and forty-five subjects (113 men and 32 women) with CKD (Stage 3 and Stage 4) participated this retrospective study. The concentration of sdLDL-C was measured in samples from 145 CKD patients between 2010 and 2012 during a four-year follow-up period. RESULTS: A total of eight fatal cardiovascular events (CVs) and 46 nonfatal CVs were registered in the four-year follow-up period. Multivariate Cox regression analysis showed that sdLDL-C [1.278, 95 % (1.019-1.598)] and sdLDL-C/LDL-C [2.456, 95 % (1.421-15.784)], at final observation, were independent risks of CVs. A Kaplan-Meier survival analysis showed that patients with sdLDL-C >38 mg/dl (logrank: 4.375, P = 0.037), and sdLDL-C/LDL-C ratio >0.3 levels (logrank: 11.94, P = 0.018) were at increased risk for CVs. CONCLUSION: The results of this study indicated that for patients suffering CKD, a significant relationship exists between an elevated sdLDL-C concentration and the risk of cardiovascular disease.
Subject(s)
Cardiovascular Diseases/epidemiology , Cholesterol, LDL/blood , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/epidemiology , Aged , Comorbidity , Diabetes Mellitus/epidemiology , Female , Follow-Up Studies , Humans , Hypertension/epidemiology , Kaplan-Meier Estimate , Male , Middle Aged , Prevalence , Proportional Hazards Models , Retrospective Studies , Risk FactorsABSTRACT
Activated sludge models (ASMs) have been widely used for process design, operation and optimization in wastewater treatment plants. However, it is still a challenge to achieve an efficient calibration for reliable application by using the conventional approaches. Hereby, we propose a novel calibration protocol, i.e. Numerical Optimal Approaching Procedure (NOAP), for the systematic calibration of ASMs. The NOAP consists of three key steps in an iterative scheme flow: i) global factors sensitivity analysis for factors fixing; ii) pseudo-global parameter correlation analysis for non-identifiable factors detection; and iii) formation of a parameter subset through an estimation by using genetic algorithm. The validity and applicability are confirmed using experimental data obtained from two independent wastewater treatment systems, including a sequencing batch reactor and a continuous stirred-tank reactor. The results indicate that the NOAP can effectively determine the optimal parameter subset and successfully perform model calibration and validation for these two different systems. The proposed NOAP is expected to use for automatic calibration of ASMs and be applied potentially to other ordinary differential equations models.
Subject(s)
Wastewater , Water Purification/methodsABSTRACT
Filamentous bulking is a complicated problem in wastewater treatment plants treating various wastewaters, leading to the deterioration of the settling properties and the effluent quality. This study systematically investigated long-term effects of various carbon sources and feeding patterns on the growth of filamentous bacteria, in order to reveal the mechanism of filamentous bulking. Sludge volume index (SVI), microscopic observations, staining (Gram and Neisser staining), scan electron microscopic, and fluorescent in situ hybridization (FISH) were used to monitor the bulking and track the changes of microbial morphology and community structure of activated sludge in six lab-scale sequencing batch reactors (SBRs) fed with different carbon sources. Filamentous bulking was not observed in all SBRs under anoxic feeding pattern with a short fill time, in which SVI remained below 150 mL/g. In contrast, serious bulking (SVI > 500 mL/g) occurred under aerobic feeding pattern when fed with ethanol, propionate, acetate, and glucose, in which Thiothrix and Sphaerotilus natans proliferated as dominant filaments. Compared to glucose-fed reactor, relatively light bulking was caused in starch-fed reactor with the growth of Nostocoida limicola II. In addition, flocs in starch-fed reactor were more open and fluffy than flocs formed on readily biodegradable substrates. Finally, a framework integrating kinetic selection, diffusion selection, storage selection, and protozoa capture mechanism was proposed to explain filamentous bulking.