A One-pot-synthesized Double-layered Anticoagulant Hydrogel Tube

Extracorporeal membrane oxygenation(ECMO) has emerged as a viable treatment in severe cases of acute respiratory distress syndrome, acute respiratory failure, and adult respiratory distress syndrome. However, thromboembolic events stemming from the use of ECMO devices results in significant morbidity and mortality rates; the inner surface of the ECMO tubing comes into contact with the blood and can readily initiate coagulation. In addition, the tubing needs to be continually replaced due to thromboses on the inner tube wall, which not only increases the risk of infection but also the economic burden. Despite considerable effort, a surface modification strategy that effectively addresses these challenges has not yet been realized. In this study, we developed an integrated hollow core-shell-shell hydrogel tube of gelatin/alginate/acrylamide-bacterial nanocellulose(GAA) that meets the anticoagulant requirements for the inner tubing layer as well as the highly elastic soft material needed for the outer layer. Using static blood from healthy volunteers, we confirmed that the platelets or coagulation is not stimulated by the GAA tubing. Importantly, experiments with dynamic blood also demonstrated that the inner layer of the tubing does not elicit blood clotting. The one-pot-synthesized process may provide guidance for the design of anticoagulation tubes used clinically.     

Local and global strong solutions to continuous coagulation-fragmentation equations with diffusion

We consider the diffusive continuous coagulation-fragmentation equations with and without scattering and show that they admit unique strong solutions for a large class of initial values. If the latter values are small with respect to a suitable norm, we provide sufficient conditions for global-in-time existence in the absence of fragmentation.     

Irreversible membrane fouling in microfiltration membranes filtering coagulated surface water

Chemical coagulation has been widely used as a method to mitigate membrane fouling in MF/UF membranes used for drinking water treatment. Optimization of coagulation as pre-treatment of membrane processes has not been achieved yet: the optimum condition of coagulation for conventional treatment systems is not necessarily applicable to membrane-based treatment systems. This study investigated (physically) irreversible membrane fouling in an MF membrane used with pre-coagulation by aluminum salt. In a series of bench-scale filtration tests, feed water containing commercially available humic acid or organic matter isolated from surface water was coagulated with polyaluminum chloride (PACl) under various conditions and subsequently filtered with an MF membrane with the nominal pore size of 0.1 μm. It was found that coagulation conditions had great impacts on the degree of physically irreversible fouling. Acidic conditions improved the quality of treated water but generally caused greater physically irreversible fouling than did neutral or alkaline conditions. Also, dosage of coagulant was found to be influential on the degree of membrane fouling: high dosage of coagulant frequently caused more severe irreversible fouling. Sizes of flocs seemed to become small under acidic conditions in this study, which was indicated by high concentrations of aluminum in the permeate under acidic conditions. It is thought that small flocs produced under acidic conditions could migrate into micropores of the membrane and caused physically irreversible fouling by plugging or adsorption. These findings obtained in the bench-scale tests were verified in a long-term pilot-scale test.     

The Dispersion Science of Papermaking

Abstract

Paper is one of the most important inventions in the history of civilization, and it is an essential commodity to all people in the world. The fact that we make ubiquitous use of a score of paper products makes it easy to underestimate its value and significance. This review is intended to put into perspective the dispersion science involved in papermaking and to describe how our understanding of key processes has evolve since its conception, approximately 2000 years ago, from art to science. Paper is formed from a slurry of fibers and much smaller particles that are often called “fines” and other chemical additives. Ahead of the paper forming process the slurry is subjected to a series of steps, including treatment with polyionic species and passage through unit operations that impose shear forces on the papermaking suspension. These steps alternately disperse the solids apart or re‐gather them back together. The overall process is optimized to achieve a highly uniform product, while at the same time achieving high efficiency in retaining fines in the sheet and allowing water to drain relatively quickly from the wet paper as it is being formed. As we approach the 1900‐year anniversary of the first detailed account of the papermaking process, it is the goal of this review to explore the scientific principles that underlie the art of papermaking, emphasizing the state of dispersion of the fibrous slurries during various stages of the manufacturing process. Some concepts that arise out of the experience of papermakers have potential applications in other fields.     

Chitosan for coagulation/flocculation processes - An eco-friendly approach

Chitosan is a partially deacetylated polymer obtained from the alkaline deacetylation of chitin, a biopolymer extracted from shellfish sources. Chitosan exhibits a variety of physico-chemical and biological properties resulting in numerous applications in fields such as cosmetics, biomedical engineering, pharmaceuticals, ophthalmology, biotechnology, agriculture, textiles, oenology, food processing and nutrition. This amino-biopolymer has also received a great deal of attention in the last decades in water treatment processes for the removal of particulate and dissolved contaminants. In particular, the development of chitosan-based materials as useful coagulants and flocculants is an expanding field in the area of water and wastewater treatment. Their coagulation and flocculation properties can be used to remove particulate inorganic or organic suspensions, and also dissolved organic substances. This paper gives an overview of the main results obtained in the treatment of various suspensions and solutions. The effects of the characteristics of the chitosan used and the conditions in solution on the coagulation/flocculation performance are also discussed.     

A Simple Approach for Removal of Carbaryl and Its Monitoring in Water Matrices

Abstract

Carbaryl, 1-napthyl N-methyl carbamate, is an extremely, broad spectrum, contact action insecticide having wide acceptance because of its low mammalian toxicity and less persistent nature. Because Carbaryl is widely used in monsoon season, it finds its way into aquatic environment.

The feasibility of Carbaryl removal by alum coagulation, was checked and found to be suitable for 98% removal of Carbaryl along with efficient turbidity removal in water matrices. The low level monitoring of Carbaryl was performed by spectroscopic technique.     

强力霉素废水的吸附-混凝预处理研究

根据强力霉素废水的特点,采用吸附-混凝联合处理工艺对其进行预处理研究。筛选出最佳吸附剂、混凝剂、助凝剂,考察了其投加量、pH、反应时间、搅拌强度等因素对处理效果的影响。实验表明,选用粉煤灰作为吸附剂、聚合氯化铝(PAC)作为混凝剂、羟乙基田菁胶(ESG)作为助凝剂,F-去除率达到99.9%,氟浓度降至10mg/L以下;化学需氧量(CODCr)去除率达到37.5%,生化需氧量/化学需氧量(BOD5/CODCr)由原来的小于0.1提高至0.16,提高了原废水的可生化性。而且处理后的灰渣烧制成砖块,不会对环境造成二次污染,达到了以废治废的目的。     

磁场对含Ni废水混凝的影响

对不溶性强磁性水污染物、高梯度磁处理技术已显示了其速度快、效率高、成本低等优点,并受到人们的注目,但对于弱磁性悬浮物及可溶性磁性物质来说,目前所采用的加磁种的方法,因其工艺复杂、成本高而无法推广,如何选择合理的处理方法,是废水磁分离技术的一个重要研究课题,磁场作为混凝的强化手段,国外已有一些研究,但国内尚未见报道,本文研究了非均匀磁场对含Ni废水混凝处理的影响及相关的各种因素。     

多光子非线性Compton散射对等离子体中颗粒成长的影响

应用等离子体颗粒成长模型和多光子非线性Compton模型,研究了多光子非线性Compton散射对等离子体中颗粒成长的影响。提出了将入射光和多光子非线性Compton散射光作为颗粒成长的新机制,对颗粒凝合截面、凝合系数、颗粒收集的电子流和离子流的表达式进行了修正。结果表明,等离子体参数的变化与多光子非线性Compton散射成分、电子散射前的初始速度、入射角、与电子同时作用的光子数等因素有关。散射使生长过程中收集离子机制和凝合机制增强,颗粒的凝合截面增大,颗粒半径较快的非均匀增长。