Exploring and comparing the roles of Ca2+ and Mg2+ in small-sized natural organics-induced charged nanofiltration membrane fouling
SEPARATION AND PURIFICATION TECHNOLOGY
Authors: Song, Yuefei; Li, Xifan; Li, Chen; Li, Jingmai; Dong, Zhaoqi; Zhang, Mengnan; Qi, Pengfei; Bai, Xueshuang; Jiang, Kai
Abstract
This study was conducted to systematically investigate how Ca2+/Mg2+ interacted with the preserved humic acid components after UF filtration (PHACUF) to cause fouling of nanofiltration (NF) membrane. Inherent characteristics including molecular weight distribution, charge, wettability, hydrodynamic size of PHACUF and its fractions under predetermined conditions and differences in PHACUF-induced NF membrane fouling behaviors, surface characteristics in the absence/presence of Ca2+/Mg2+ were analysed and explored, respectively. Microinteraction forces between PHACUF and Ca2+/Mg2+ were also compared. The results manifested that contrary to many typical reports about HA foulant, Mg2+ exhibited superior charge screening effect with PHACUF, and performance in accelerating hydrodynamic colloid size, dense membrane fouling compared to Ca2+. O 1s bonding energy shift and ITC data provided powerful and quantified evidences that Mg2+ could coordinate with PHACUF more effectively and cause more serious fouling deposits on NF membrane surfaces than Ca2+, presumably due to its favorable specific charge and binding ability. In terms of its own components, HOA fraction seems destined to preferentially bond with most of Ca2+ and Mg2+ ions and constitute a high proportion of membrane fouling loading because it possesses the highest charge density and content compared with other fractions in near-actual natural surface water circumstance.
Aligning Hearing Aid and Cochlear Implant Improves Hearing Outcome in Bimodal Cochlear Implant Users
OTOLOGY & NEUROTOLOGY
Authors: Holtmann, Laura Christine; Janosi, Anna; Bagus, Heike; Scholz, Tim; Lang, Stephan; Arweiler-Harbeck, Diana; Hans, Stefan
Abstract
Objective: Patients with unilateral deafness and residual hearing on the contralateral ear can benefit from a cochlear implant (CI) on one side and a hearing aid (HA) on the other. However, hearing improvement among these patients is heterogenous. Interindividual differences in bimodal benefit may be caused by a mismatch of CI and HA. The aim of this study was to clinically apply a HA fitting strategy and to evaluate hearing outcome with and without a dedicated bimodal fitting formula. Study Design: Prospective non-randomized study. Setting: Tertiary referral center. Patients: Twelve patients using a CI processor and a conventional HA were enrolled. Before and after the new HA had been adjusted to the patient and linked to the CI, pure-tone audiometry and localization tests were performed. Speech perception was determined in quiet and noise. Tests were repeated after 6 and 12 weeks. To evaluate the subjective listening comfort two questionnaires (Oldenburg Inventory and HISQUI(19)) were assessed. Intervention: Therapeutic. Results Main outcome measure: Word recognition in quiet, sentence recognition in noise. Speech perception in noise improved significantly: directed suppression of noise helped to segregate the target speech signal from a mixture of sounds or competing speakers. Evaluation of the questionnaires revealed a positive subjective hearing experience compared with patients' initial settings of the devices. Conclusion: By linking CI and HA hearing and speech perception can be improved. However, good counselling at the outset is essential to obtain enhanced outcome.