81,638 research outputs found
High-performance f-GO/MWCNTs-COOH nanohybrid-based polylactic acid mixed matrix membrane for wastewater treatment
No full textTo enhance the green polylactic acid (PLA) membrane's efficiency for removing organic materials, self-assembled functionalized graphene oxide carboxylic multi-walled carbon nanotubes (f-GO/MWCNTs-COOH) was incorporated into the membrane matrix followed by immersion precipitation. The successful formation of the negatively charged f-GO/MWCNTs-COOH nanohybrid was verified by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and zeta potential analyzer. The effect of different nanohybrid contents (1.5, 3 and 6 wt%) on the PLA membrane performance was investigated. The prepared mixed matrix membranes were analyzed by FT-IR, XRD, SEM, contact angle, porosity, and pore size analysis. Synthetic organic foulant bovine serum albumin (BSA), humic acid (HA) solutions were utilised to test the antifouling behaviour of membranes. In addition, raw wastewater from a wastewater treatment plant (WWTP) was used to further assess the performance of the membranes. The results indicated that with only 3 wt% f-GO/MWCNTs-COOH nanohybrid in the PLA membrane matrix, the fouling tendency was attenuated (superior rejection rates for BSA and HA of 96 % and 98 %, respectively.) and the pure water flux was increased to almost 80 L/m2hbar, compared to the neat PLA membrane (27 L/m2hbar), without compromising the high organic removal efficiency. According to the results of this study, the f-GO/MWCNTs-COOH nanohybrid has great potential to enhance the performance of mixed matrix membranes in raw wastewater treatment applications
Correlation between bacterial community structure and performance efficiency of a full-scale wastewater treatment plant
No full textThis study aimed at understanding how bacterial communities fluctuate and correlate with wastewater treatment plant (WWTP) efficiency over a ten-month period. Illumina sequencing of 16 s rRNA gene variable regions was performed on genomic DNA extracted from aeration tank samples collected twice a week and analyzed using the Bioinformatics Tool Quantitative Insights into Microbial Ecology 2 (QIIME2). This was done in order to track and relate changes in the bacterial community in the aeration tank to the performance of the plant. The results revealed that the most dominant bacterial phyla present in the aeration tank were Proteobacteria (15 %–40 % of total sequences in all samples), and Bacteroidetes (14 %–41 %) followed by Planctomycetes (2 %–23 %), Patescibacteria (2 %–13 %), Chloroflexi (3 %–12 %), and Nitrospirae (1 %–9 %). Beta analysis revealed clear shifts in the bacterial communities with an overall cyclic pattern that correlated well with the month of the year the aeration tank samples were collected through which samples clustered in groups with samples taken in the same month clustering closer together. Planctomycetes and Bacteroidetes were enriched during the colder, while Chloroflexi and Nitrospirae were enriched during the warmer months. Lastly, it was also found that the efficiency of biological oxygen demand (BOD) and ammonia-N removals were significantly correlated (P < 0.05) with the occurrence of Bdellovibrio bacterial genus and members of Hydrogenophilaceae, respectively. This study is the first to provide this level of temporal resolution on bacterial community fluctuations in a full scale WWTP in the UAE
Robustness of Triple Sampling Inference Procedures to Underlying Distributions
No full textIn this study, the sensitivity of the sequential normal-based triple sampling procedure for estimatingthe population mean to departures from normality is discussed. We assume only that the underlyingpopulation has finite but unknown first six moments. Two main inferential methodologies areconsidered. First point estimation of the unknown population mean is investigated where a squarederror loss function with linear sampling cost is assumed to control the risk of estimating the unknownpopulation mean by the corresponding sample measure. We find that the behaviour of the estimatorsand of the sample size depends asymptotically on both the skewness and kurtosis of the underlyingdistribution and we quantify this dependence. Moreover, the asymptotic regret of using the triplesampling inference instead of the fixed sample size approach, had the nuisance parameter beenknown, is a finite but non-vanishing quantity that depends on the kurtosis of the underlyingdistribution. We also supplement our findings with a simulation experiment to study the performanceof the estimators and the sample size in a range of conditions and compare the asymptotic and finitesample results. The second part of the thesis deals with constructing a triple sampling fixed widthconfidence interval for the unknown population mean with a prescribed width and coverage whileprotecting the interval against Type II error. An account is given of the sensitivity of the normal-basedtriple sampling sequential confidence interval for the population when the first six moments areassumed to exist but are unknown. First, triple sampling sequential confidence intervals for the meanare constructed using Hall’s (1981) methodology. Hence asymptotic characteristics of the constructedinterval are discussed and justified. Then an asymptotic second order approximation of a continuouslydifferentiable and bounded function of the stopping time is given to calculate both asymptoticcoverage based on a second order Edgeworth asymptotic expansion and the Type II error probability.The impact of several parameters on the Type II error probability is explored for various continuousdistributions. Finally, a simulation experiment is performed to investigate the methods in finite samplecases and to compare the finite sample and asymptotic results
Results of the Heart Protection Study: Can we still assume a class effect?
No full textStatins share several common features including the mechanism of action, i.e. inhibition of HMG-CoA reductase, as well as LDL-cholesterol (LDL-C) and triglyceride lowering properties. However, statins show minor differences in chemical structure, lipophilicity that could translate into a different pharmacological properties. For example, simvastatin exerted a more favorable effect on HDL-C levels than did atorvastatin when higher doses of the two drugs were compared. Finally, the major considerations to chose between statins for CVD patient therapy include clinical benefits and safety (i.e. evidence-based medicine). Primary prevention trials with pravastatins and lovastatin and secondary prevention trials with pravastatin, fluvastatin and simvastatin have established the clinical benefits of statins. In addition, HPS study was designed to investigate the benefits of simvastatin 40 mg in a broad range of patients at high risk for heart disease including women, the elderly and those with a history of hearth attacks, diabetes, hypertension or vascular disease. The results show the ability of simvastatin to reduce all causes of mortality, vascular death and cardiovascular morbidity. The trial also confirms the safety of simvastatin 40 mg although 60% of patients were receiving additional pharmacological treatment. In summary, it appears that statins are not the same and the choice of the more appropriate statin in high-risk patients should be driven by the evidence-based medicine both in terms of safety and efficacy
Assessment of Microbial Community Structure and Function in Serially Passaged Wastewater Electro-Bioreactor Sludge: An Approach to Enhance Sludge Settleability
No full textSeveral studies have been carried out to understand bulking phenomena and the importance of environmental factors on sludge settling characteristics. The main objective of this study was to carry out functional characterization of microbial community structure of wastewater electro-bioreactor sludge as it undergoes serial passaging in the presence or absence of a current density over 15 days. Illumina MiSeq sequencing and QIIME were used to assess sludge microbial community shifts over time. (α) and (β) diversity analysis were conducted to assess the microbial diversity in electro-bioreactors. A phylogeny-based weighted UniFrac distance analysis was used to compare between bacterial communities while BIO-ENV trend and Spearman's rank correlation analysis were performed to investigate how reactor operational parameters correlated with bacterial community diversity. Results showed that the removal efficiency of soluble chemical oxygen demand (sCOD) ranged from 91-97%, while phosphorous (PO43--P) removal was approximately 99%. Phylogenetic analysis revealed stark differences in the development of sludge microbial communities in the control and treatment reactor. There was no mention of any studies aimed at characterizing functional microbial communities under electric field and the results communicated here are the first, to our knowledge, that address this gap in the literature
Models for production and inventory systems for deteriorating items with a supply-chain perspective
No full textThis thesis in the field of inventory management for deteriorating items studies the effects of deterioration on optimal policies in inventory and production-inventory models. Four different models are developed and analysed to address some of the gaps identified in this part of the inventory management literature. The first two models have been studied adopting the classic approach towards inventory modelling, where the holding cost is assumed to be proportional to a known exogenous unit holding cost parameter. Taking this approach, first a two-echelon (single-buyer, single-supplier) model is investigated in which the capacity is considered to be limited. In this model also the exact inventory level over time of the supplier is obtained whereas the literature to date has only considered the average inventory level. As the analysis shows, this results in a complex model, and therefore a heuristic is developed. In the second model, a single supplier, multiple buyers system is developed where there is a (in)finite production rate. It has been identified that the literature fails to calculate accurately the average inventory level of the supplier in situations where the production rate is finite. In this model this issue has been addressed, and further analysis reveals the significance of the more accurate modelling approach developed. The literature evaluates inventory models in different ways in terms of objective function. A body of research is identified in the literature that assumes an equivalence between profit maximisation and cost minimisation, and it often seems logical to discard revenues and minimise the cost function. This equivalence, however, is not always easily established when the objective function is to maximise the Net Present Value (NPV) of the profit function. In the third model of this thesis, this equivalence is analysed in detail, and it is shown that taking a cost minimisation model instead of a profit maximisation objective in some cases should be done cautiously and in the best case only adopted after establishing the relevant equivalence conditions using NPV Equivalence Analysis (NPVEA). Finally, in a fourth model a two-echelon supply chain with capacity constrains is developed using the NPV criterion. In this model a modification in the inventory level is suggested which makes the model more practical compared to the existing models in cases that the customers are serviced from the own warehouse
Purification and structure elucidation of paraplantaricin TC318, a new lantibiotic produced by Lactobacillus paraplantarum OSY-TC318
No full textPoster Division: Health Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)A new Lactobacillus paraplantarum strain isolated from a Turkish cheese showed potent antimicrobial activity that inhibits Bacillus cereus, Micrococcus luteus, Lactobacillus casei and Pediococcus pentosaceus. The producer strain, designated Lactobacillus paraplantarum OSY-TC318, was identified using rapid MALDI-TOF mass spectrometry (MS), 16S rDNA sequencing and further confirmed by whole genome sequencing (WGS). The antimicrobial agent was extracted from cells of OSY-TC318 with 70% isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry. The MS and WGS analyses, taken together, elucidated the structure of the novel lantibiotic consisting of 22 amino acids and four thioether bridges. The molecular mass of the new lantibiotic, designated paraplantaricin TC318, is 2263.900 Da. Paraplantaricin TC318 contains one didehydroalanine (Dha), one didehydrobutyric acid (Dhb), one methyllanthionine (MeLan), two lanthionine (Lan) residues and a C-terminal S-[(Z)-2-aminovinyl]-D-cysteine (AviCys) residue. The proposed primary sequence of paraplantaricin TC318 is: F-K-A-W-Dha-L-A-Abu-F-G-A-G-H-Dhb-G-A-F-N-A-F-A. This lantibiotic, which differs from mutacin 1140 at positions 9, 12, 13 and 20, is a new member of the epidermin group in class I lantibiotic.A five-year embargo was granted for this item
A Relational Unsupervised Approach to Author Identification
No full textIn the last decades speaking and writing habits have changed.
Many works faced the author identification task by exploiting frequencybased
approaches, numeric techniques or writing style analysis. Following
the last approach we propose a technique for author identification
based on First-Order Logic. Specifically, we translate the complex data
represented by natural language text to complex (relational) patterns
that represent the writing style of an author. Then, we model an author
as the result of clustering the relational descriptions associated to the
sentences. The underlying idea is that such a model can express the typical
way in which an author composes the sentences in his writings. So,
if we can map such writing habits from the unknown-author model to
the known-author model, we can conclude that the author is the same.
Preliminary results are promising and the approach seems viable in real
contexts since it does not need a training phase and performs well also
with short texts
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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