4,915 research outputs found
Potential therapeutic applications of microbial surface-active compounds
No full textNumerous investigations of microbial surface-active compounds or biosurfactants over thepast two decades have led to the discovery of many interesting physicochemical and biologicalproperties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies
Numerical modeling of an integrated OMBR-NF hybrid system for simultaneous wastewater reclamation and brine management
No full textThe osmotic membrane bioreactor (OMBR) is an energy-efficient wastewater purification technique that integrates a membrane bioreactor (MBR), a forward osmosis (FO) membrane, and a draw solution. The main objective of this study was to develop a hybrid model that combines an OMBR with nanofiltration (NF) for simultaneous wastewater reclamation and brine management. In this model, reverse osmosis (RO) reject brine and wastewater were used as draw and feed solutions, respectively. The results from the model suggested that a stable pure water flux of 2.10 dm/d can be obtained with a water salinity of 352.62 mg/L at an effective osmotic pressure of 11.42 bar. To further investigate the model, sensitivity analysis of five main system inputs of the hybrid OMBR-NF system was carried out. The results showed that the water flux can be improved by enhancing the mass diffusion coefficient on the draw solution side (K-d) and the salt concentration of the final draw solution (X-di). In addition, the water flux can be improved by reducing the internal concentration polarization (ICP) effect. For instance, the water flux increased from around 1.90 to 2.33 dm/d when K-ICP was decreased from 0.56 to 0.36 d/dm. Lastly, it was found that X-di was the main influence on the permeate water quality; increasing it from 20,000 to 70,000 mg/L caused the water salinity to increase from 100 to 352 mg/L. Overall, this novel hybrid system can be used to achieve better water quality and reduce environmental pollution from highly concentrated brines
Preparation of novel polyvinylidene fluoride (PVDF)-Tin(IV) oxide (SnO2) ion exchange mixed matrix membranes for the removal of heavy metals from aqueous solutions
No full textGlobal consideration has been growing recently to tackle the toxic and carcinogenic effects of heavy metal presence in water streams. In this work, novel polyvinylidene fluoride (PVDF)/tin(IV) oxide (SnO2) ion exchange membranes were prepared via the phase inversion method and their performance and properties were analyzed. The results showed that the addition of SnO2 nanoparticles (SnNPs) led to an improvement in the pure water flux from 25.5 ± 1.5 L/m2.h in the pristine PVDF membrane to 250.5 ± 12.5 L/m2·h in the 1.00 wt% PVDF/SnNPs membranes. This was related to the increase in the overall porosity and hydrophilicity of the membranes. Additionally, the 0.25 wt% PVDF/SnNPs membrane reported the highest tensile strength equal to 21.3 ± 0.6 MPa compared to only 14.3 ± 0.4 MPa in the pristine PVDF membrane. Lastly, the maximum removal of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ was achieved by the 0.25 wt% PVDF/SnNPs membrane with around 93.9 ± 1.7, 92.8 ± 1.3, 82.3 ± 2.0, 70.7 ± 1.1, and 63.9 ± 1.5%, respectively, compared to 93.5 ± 1.3, 92.9 ± 1.7, 68.3 ± 2.1, 50.3 ± 1.8, and 50.3 ± 1.4% in the pristine PVDF membrane. The mechanism of removal was predicted to be a combination of ion exchange/adsorption, inner-sphere complexations and electrostatic attraction between the metal ions and the SnNPs. Such a PVDF/SnNPs membranes have great potential in the field of wastewater treatment
Rubaies of İbrahim Aczî kendî (The last 180 rubaies)
No full text1881-1965 yılları arasında Konya'da yaşayan İbrahim Aczî Kendî, Konya'nın XX. yüzyılda yetiştirdiği önemli şair, gazeteci, araştırmacı, yazar, mutasavvıf ve folklorculardandır. Konya'da öğretmenlik yapan İbrahim Aczî Kendî, Arapça ve Farsça öğrenerek kendini geliştirmiş, tasavvuf, edebiyat ve tarihle ilgili kitaplar hazırlamıştır. İbrahim Aczî Kendî'nin bizzat kendisinin kaleme aldığı, tek nüshası Yusuf Ağa Kütüphanesinde 10465/1 numara ile kayıtlı olan Devr-i Zaman adlı eseri, 360 Farsça rubâî ve bu rubâîlerin Osmanlı Türkçesiyle yazılmış açıklamalarından oluşmaktadır. Bu çalışmada İbrahim Aczî Kendî'nin hayatı incelenmiş, Devr-i Zaman adlı eserinde bulunan 360 rubâînin son 180 tanesi çalışılmıştır. Her bir rubâînin Farsça ana metinleri bilgisayar ortamına aktarılmış, bazen sadece tercüme, bazen de çeşitli açıklamalar içeren Osmanlı Türkçesiyle yazılan kısımlar ise latin harfleriyle aktarılmıştır. İbrahim Aczî Kendî, bu çalışmada ele alınan rubâîlerinde, genellikle ilahi aşk, toplumsal ahlâk, zamandan şikâyet, riya ve kibirden uzak durmanın gerekliliği gibi birçok konuya değinmiştir.İbrahim Aczî Kendî who lived the years between 1881 and 1965 in Konya is an important poet, a journalist, an investigate author, a mystic and a folklorist who raised by Konya in 20th century. İbrahim Aczî Kendi, worked as a tutor in Konya, improved himself by learning Arabian and Persian, prepared books about mysticism, literature and history. Devr-i zaman, which is written by İbrahim Aczî Kendî by himself and whose only transcript is registered with the number 104657/1 in Yusuf Ağa Library, is made of 360 Persian rubaies and their explanation which is written in Ottoman Turkish. In this study İbrahim Aczî Kendî's life and last 180 of 360 Persian rubaies are studied. Each of rubaies' Persian main texts are transferred to electronic environment. Parts that sometimes include translation, sometimes also include various types of explanations written Ottoman Turkish are transferred with Latin letters. İbrahim Aczî Kendî, rubaies that handled in this study, touches on many topics, such as sociel ethics, complaints about today's youht, hypocrisy and staying away from and arrogance
Optimization of washing conditions with biogenic mobilizing agents for marine fuel-contaminated beach sands
No full textWashing is a rapid and effective treatment to remediate contaminated sands impacted by oil spills, although synthetic additives used to increase extraction efficiency may cause additional pollution issues due to their intrinsic toxicity and very often low biodegradability. In this study, different biogenic mobilizing agents (soybean lecithins, cyclodextrins, cholic acids, plant-derived cleaners, rhamnolipids and sophorolipids) were tested in the washing of beach sands artificially contaminated with the Intermediate Fuel Oil IFO-180. Among these, a de-oiled soybean lecithin (SL-1), hydroxypropyl-beta-cyclodextrins (HPB-CD) and sophorolipids (SR) achieved hydrocarbon removals close to those attained with the synthetic surfactant Triton X-100 (TX) in preliminary washing tests carried out at constant mixing rate, water/sand ratio and IFO-180 contamination level using agents concentrations close to their critical micelle concentration (0.1% and 1% w/v for microbial and non-microbial agents, respectively). The effects of agent concentration, water/sand ratio, mixing rate and IFO-180 contamination on hydrocarbons removal were modelled using face-centred central composite design and ANOVA. Optimal washing parameters for sand contamination levels in the range 0.5-20 g/kg were identified with response surface methodology. While HPB-CD and SR performed equally to TX only at low sand contaminations, SL-1 attained hydrocarbon removal higher or equal to that of TX at any IFO-180 contamination and at lower application rates. SL-1 also outperformed TX when minimizing the water/sand ratio, i.e., the volume of water used. Considering its lower toxicity, higher biodegradability and higher hydrocarbon removal efficiencies, SL-1 is an effective and environmentally sustainable alternative to synthetic surfactants in washing treatments for marine fuel-contaminated sands
External interventions and the duration of civil wars
No full textThe authors combine an empirical model of external intervention, with a theoretical model of civil war duration. Their empirical model of intervention allows them to analyze civil war duration, using"expected"rather than"actual"external intervention as an explanatory variable in the duration model. Unlike previous studies, they find that external intervention is positively associated with the duration of civil war. They distinguish partial third-party interventions that extend the length of war, from multilateral"peace"operations, which have a mandate to restore peace without taking sides - and which typically take place at war's end, or at least when both sides have agreed to a cease-fire. In a future paper, the authors will examine whether partial third-party interventions - whatever their effect on a war's duration - increase the risk of war's recurrence. If that proves true, then even if interventions reduce the length of civil war, they may do so at the cost of further destabilizing the political system, and sowing the seeds of future rebellion.Children and Youth,Peace&Peacekeeping,Post Conflict Reconstruction,Post Conflict Reconstruction,International Affairs,Post Conflict Reconstruction,Social Conflict and Violence,Peace&Peacekeeping,Post Conflict Reconstruction,International Affairs
Facile synthesis and characterization of super-hydrophobic Fe2O3 for membrane distillation
No full textHighly selective heavy metal ions membranes combining sulfonated polyethersulfone and self-assembled manganese oxide nanosheets on positively functionalized graphene oxide nanosheets
No full textThis study presents the synthesis of a novel graphene oxide-manganese oxide (GO-MnO2) nanohybrid and its incorporation into sulfonated polyethersulfone (SPES) ultrafiltration (UF) membranes for wastewater treatment applications. The nanohybrid was first prepared by grafting ethylenediamine (ED) onto the edge of GO followed by direct mixing with the MnO2 nanosheets. The composite membranes were prepared via the phase inversion method and optimized by varying the concentration of the GO-MnO2 nanohybrid (0-6 wt%). The membranes were characterized using scanning electron microscopy, surface zeta potential, water flux, porosity, among others. The results showed that the pure water flux increased from 59.5 +/- 2.5 L.m(-2).h(-1) in the pristine SPES membrane to 129.7 +/- 4.1 L.m(-2).h(-1) in the SPGM4 (4 wt% GO-MnO2). Furthermore, the heavy metal ions rejection improved from 70.1, 49.1, and 55.8% for Cu2+, Zn2+, and Ni2+ ions, respectively, in the pristine SPES membrane to 81.1, 64.0, and 67.4% in the SPGM4 membrane. Also, the composite membranes revealed improvement in the anti-fouling properties over the pristine SPES membrane. For example, the SPGM4 membrane recovered 90.5 +/- 2.9% of its initial flux compared to only 72.6 +/- 3.1% in the pristine membrane after 4 cycles of heavy metal filtration and simple acid cleaning steps. Overall, the addition of GO-MnO2 nanohybrid enhanced the properties of the pristine SPES, creating new potential for such composite membranes in the wastewater treatment industry
Investigation of Graphene Oxide (GO)- Manganese Oxide (MnO2) Nanocomposite in Metal Ions Adsorption from Wastewater
No full textPreparation of microfiltration cellulose-nanosized zirconium phosphate composite membranes for the remediation of toxic metals from wastewater
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