Nondestructive 3D Imaging and Quantification of Hydrated Biofilm-Sediment Aggregates Using X-ray Microcomputed Tomography.

Biofilm-sediment aggregate (BSA) contains a high water content, either within internal pores and channels or bound by extracellular polymeric substances (EPS) forming a highly hydrated biofilm matrix. Desiccation of BSAs alters the biofilm morphology and thus the physical characteristics of porous media, such as the binding matrix within BSA and internal pore geometry. Observing BSAs in their naturally hydrated form is essential but hampered due to the lack of techniques for imaging and discerning hydrated materials. Generally, imagery techniques (scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam nanotomography (FIB-nt)) involve the desiccation of BSAs (freeze-drying or acetone dehydration) or prevent differentiation between BSA components such as inorganic particles and pore water (confocal laser scanning microscopic (CLSM)). Here, we propose a novel methodology that simultaneously achieves the 3D visualization and quantification of BSAs and their components in their hydrated form at a submicron resolution using X-ray microcomputed tomography (µ-CT). It enables the high-resolution detection of comparable morphology of multiphase components within a hydrated aggregate: each single inorganic particle and the hydrated biofilm matrix. This allows the estimation of aggregate density and the illustration of biofilm-sediment binding matrix. This information provides valuable insights into investigations of the transport of BSAs and aggregate-associated sediment particles, contaminants (such as microplastics), organic carbon, and their impacts on aquatic biogeochemical cycling.

Audiologic and surgical outcomes of a novel, nonpercutaneous, bone conducting hearing implant.

OBJECTIVE: To assess the selection criteria, surgical technique, audiologic, and quality of life outcomes for a novel, nonpercutaneous bone conductor hearing aid. STUDY DESIGN: Retrospective case review. SETTING: Secondary otology practice. PATIENTS: Eighteen patients (16 adults and 2 children). INTERVENTION: Implantation of unilateral (n = 16) or bilateral (n = 2) devices. MAIN OUTCOME MEASURES: Mean preoperative and postoperative air conduction and bone conduction free-field testing, BKB-SIN aided and unaided at 0-degree 70 dB SPL, Speech, Spatial, and Qualities of Hearing Scale (SSQ), aided and unaided measures of localization and discrimination in single-sided deafness (SSD), surgical complications. RESULTS: Implants have been fixed under general or local anesthesia without perioperative complications. Two patients noted minor skin irritation only. Audiologic gain was greatest for those with bilateral conductive loss (21.9 ± 10.4 dB HL). For those with bilateral and unilateral mixed loss, gain was 6.2 ± 5.3 dB HL and 5.5 ± 6.5 dB HL, respectively. A greater improvement was seen with BKB-SIN at 70 dB SPL at 0 with all groups except for SSD, gaining statistically significant benefit. Localization and discrimination studies in patients with SSD or unilateral conductive loss failed to detect benefit from aiding. SSQ scores show an improvement in all domains for each patient group. CONCLUSION: The surgical procedure requires no specialized equipment and can be performed as a day case. This device complements treatment for patients requiring bone conduction aids and presents as an alternative to conventional percutaneous bone-anchored implants.