Water softening using a light-responsive, spiropyran-modified nanofiltration membrane

A novel technique for the covalent attachment of a light-responsive spiropyran onto polyamide thin film composite nanofiltration (NF) membranes in a one-step reaction using low-energy electron beam technology is described. The effect of illumination of the immobilized spiropyran was studied, as well as the resulting membrane properties with respect to MgSO4 retention, water permeability rate, and chlorine resistance. Electron beam irradiation showed a direct effect on the transformation of the rough PA NF membrane surface into a ridge-and-valley structure. Upon UV light irradiation, the spiropyran transformed into zwitterionic merocyanine, which had shown MgSO4 removal of >95% with water permeation rates of 6.5 L/(m2·h·bar). Alternatively, visible light was used to convert merocyanine to spiropyran, which achieved >95% of MgSO4 retention with a water flux of around 5.25 L/(m2·h·bar). The modified NF membranes showed higher chlorine resistance as well as a higher normalized water flux as compared to the reference membrane, without a loss of ion retention. All the NF membranes were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. This study demonstrates a simple and inexpensive method for the immobilization of molecules onto polymeric membranes, which may be applied in water softening

A Multi-Country, Single-Blinded, Phase 2 Study to Evaluate a Point-of-Need System for Rapid Detection of Leishmaniasis and Its Implementation in Endemic Settings

With the advancement of isothermal nucleic acid amplification techniques, detection of the pathogenic DNA in clinical samples at point-of-need is no longer a dream. The newly developed recombinase polymerase amplification (RPA) assay incorporated in a suitcase laboratory has shown promising diagnostic efficacy over real-time PCR in detection of leishmania DNA from clinical samples. For broader application of this point-of-need system, we undertook a current multi-country diagnostic evaluation study towards establishing this technique in different endemic settings which would be beneficial for the ongoing elimination programs for leishmaniasis. For this study purpose, clinical samples from confirmed visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL) patients were subjected to both real-time PCR and RPA assay in Bangladesh, India, and Nepal. Further skin samples from confirmed cutaneous leishmaniasis (CL) patients were also included from Sri Lanka. A total of 450 clinical samples from VL patients, 429 from PKDL patients, 47 from CL patients, and 322 from endemic healthy/healthy controls were under investigation to determine the diagnostic efficacy of RPA assay in comparison to real-time PCR. A comparative sensitivity of both methods was found where real-time PCR and RPA assay showed 96.86% (95% CI: 94.45–98.42) and 88.85% (95% CI: 85.08–91.96) sensitivity respectively in the diagnosis of VL cases. This new isothermal method also exhibited promising diagnostic sensitivity (93.50%) for PKDL cases, when a skin sample was used. Due to variation in the sequence of target amplicons, RPA assay showed comparatively lower sensitivity (55.32%) than that of real-time PCR in Sri Lanka for the diagnosis of CL cases. Except for India, the assay presented absolute specificity in the rest of the sites. Excellent concordance between the two molecular methods towards detection of leishmania DNA in clinical samples substantiates the application of RPA assay incorporated in a suitcase laboratory for point-of-need diagnosis of VL and PKDL in low resource endemic settings. However, further improvisation of the method is necessary for diagnosis of CL

Carbon nanotube functionalizations and the development of carbon nanotube-enzyme hybrid catalyst for the degradation of 3,4-dihydroxybenzoic acid pollutant in water / Rasel Das

The efficient handling of both the persisting and newly emerging pollutants is a must, since they are continuously defiling the limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. The 3,4-Dihydroxybenzoic Acid (3,4-DHBA) is a major phenol-type toxic water pollutant having detrimental effects on animal and human health. It causes oxidative stress, neurotoxicity, hepatotoxicity and skin cancer when ingested at high levels by animals (≥ 1.0 μmole) and humans (≥ 5.0 mM). Currently, 3,4-DHBA is handled by a few methods such as adsorption, chemical oxidation and microbial decontaminations which are non-specific, insensitive, time consuming, costly and generating chemical masses to the environment. Recently, immobilized enzymes onto nanomaterial supports have been evolved a new generation of Nanobiohybrid catalysts which have versatile applications in waste water purifications. Protocatechuate 3,4-dioxygenase (3,4-POD) has long been used for the degradation of 3,4-DHBA. However, immobilizing 3,4-POD onto nanomaterial for enhancing its stabilities, reusability and reduced cost has remained unexplored. Here we filled up this gap by developing a novel Nanobiohybrid catalyst through covalent immobilization of 3,4-POD onto multi-walled carbon nanotube (MWCNT) surfaces. MWCNTs were selected since they are low-cost materials with large surface area, high aspect ratio, greater chemical reactivity, and less chemical mass and adverse environmental impact. Unfortunately, pristine MWCNTs are hydrophobic and often contaminated with various impurities such as amorphous carbons, metals and ashes which hinder its conjugation with biomolecules. Here we attempted to develop simple methods for MWCNT purification and functionalization with bio-conjugating functionalities with added water dispersion properties. We observed that HCl/H2O2 treatment annihilated more amorphous carbons and metals from the MWCNTs compared with HCl alone and KOH/H2O2 methods. On the other hand, H2SO4/HNO3 functionalized MWCNTs (F-MWCNTs) were more soluble in water because of their higher number of -COOH functionalities than those of HNO3/H2O2 and KMnO4 functionalizations. Thus HCl/H2O2 purified and H2SO4/HNO3 F-MWCNT was used as support matrix for 3,4-POD immobilization. Convincing results from scanning electron microscopy, transmission electron microscopy, atomic force microscopy, attenuated total reflectance infrared and ultraviolet-visible spectroscopy studies confirmed that the 3,4-POD was successfully immobilized onto F-MWCNT surfaces, and maximum loading was found 1060 μg of 3,4-POD/mg of F-MWCNTs. Circular dichroism spectra showed that the Nanobiohybrid could experience with 44% of structural changes to its free 3,4-POD conformations that was capable to retain 93% of relative activity and about 50% of catalytic efficiency to its free 3,4-POD. In addition, Nanobiohybrid demonstrated higher alkaline and thermo stabilities as compared with free 3,4-POD. Nanobiohybrid retained 56% of residual activity which was 41 and 39% for the free 3,4-POD at 4 and 25oC on 30 days storage, respectively. Besides, the Nanobiohybrid exhibited >60% of residual activity even after ten cycle of operations, suggesting that it could defray the production costs of free 3,4-POD for long term uses in waste water purifications. Finally, the Nanobiohybrid removed 71% of 3,4-DHBA from water in less than four hour, paving its application for the efficient removal of toxic water pollutants with reduced costs and time

Predicting Drivers’ Crash Risk Based-on Previous Crash History

Crash-prone drivers should be effectively targeted for various safety education and regulation programs because their over-involvement in crashes presents a big adverse effect on highway safety. By analyzing seven-years of crash data from Louisiana, this paper investigates crash-prone drivers’ characteristics and estimates their risk to have crashes in the seventh year based on these drivers' crash history of the past six years. The analysis results show that quite a few drivers repeatedly had crashes; seven drivers had 13 crashes in seven years; and the maximum number of crashes occurring in a single year to a single driver is eight. Actually, the 5% of drivers who had multiple crashes were responsible for 35% of the crashes that occurred in the seven years in Louisiana. Crash injury rate is also higher for drivers with multiple crashes. The probability of having crash(es) in any given year is closely related to a driver’s crash history; less than 4% of drivers with no crash in the previous six years; and slightly higher than 30% for drivers with nine or more crashes in the previous six years. There are variations in drivers’ age, gender, crash contribution factors, and type of crashes by the number of crashes. Based on the results, several suggestions are made on how to improve roadway safety through reducing crashes committed by drivers with much higher crash risk as identified by the analysis

The toxic truth about carbon nanotubes in water purification: a perspective view

Without nanosafety guidelines, the long-term sustainability of carbon nanotubes (CNTs) for water purifications is questionable. Current risk measurements of CNTs are overshadowed by uncertainties. New risks associated with CNTs are evolving through different waste water purification routes, and there are knowledge gaps in the risk assessment of CNTs based on their physical properties. Although scientific efforts to design risk estimates are evolving, there remains a paucity of knowledge on the unknown health risks of CNTs. The absence of universal CNT safety guidelines is a specific hindrance. In this paper, we close these gaps and suggested several new risk analysis roots and framework extrapolations from CNT-based water purification technologies. We propose a CNT safety clock that will help assess risk appraisal and management. We suggest that this could form the basis of an acceptable CNT safety guideline. We pay particular emphasis on measuring risks based on CNT physico-chemical properties such as diameter, length, aspect ratio, type, charge, hydrophobicity, functionalities and so on which determine CNT behaviour in waste water treatment plants and subsequent release into the environment

Multifunctional Carbon Nanotubes (CNTs): A New Dimension in Environmental Remediation

Water pollution is a serious, persistent and emerging problem not only in Malaysia but all over the world. It has negative impacts on the sustainability of water resources, aquatic flora and fauna and community health. It significantly reduces total water availability because of the lack of suitable and cost-effective pollutant treatment facilities. Current facilities for water purification are time consuming, expensive and have low affinity and efficiency to newly emerging micro pollutants in water. Carbon nanotube (CNT) based nanocomposites and hybrids have attracted huge attention for their potential in the treatment of newly emerging micropollutants in water bodies. Addition of various molecules and binders such as magnetic nanoparticles, pollutant binding and degrading receptors and enzymes has added new dimensions in the fibrous shape, high aspect ratio, large surfaces, and accessible mesopores of CNTs. In this review, we have outlined the recent progress and future prospects of multifunctional CNT-hybrids for the treatment of both conventional priority and newly emerging micropollutants in water environment. The review also has highlighted the future strategies for overcoming the shortcomings of existing techniques and materials for water purification applications