Inhibition of biofouling on reverse osmosis membrane surfaces by germicidal ultraviolet light side-emitting optical fibers.

Biofouling of membrane surfaces poses significant operational challenges and costs for desalination and wastewater reuse applications. Ultraviolet (UV) light can control biofilms while reducing chemical usage and disinfection by-products, but light deliveries to membrane surfaces in spiral wound geometries has been a daunting challenge. Thin and flexible nano-enabled side-emitting optical fibers (SEOFs) are novel light delivery devices that enable disinfection or photocatalytic oxidation by radiating UV light from light-emitting diodes (LEDs). We envision SEOFs as an active membrane spacer to mitigate biofilm formation on reverse osmosis (RO) membranes. A lab-scale RO membrane apparatus equipped with SEOFs allowed comparison of UV-A (photocatalysis-enabled) versus UV-C (direct photolysis disinfection). Compared against systems without any light exposure, systems with UV-C light formed thinner-but denser-biofilms, prevented permeate flux declines due to biofouling, and maintained the highest salt rejection. Results were corroborated by in-situ optical coherence tomography and ex-situ measurements of biofilm growth on the membranes. Transcriptomic analysis showed that UV-C SEOFs down-regulated quorum sensing and surface attachment genes. In contrast, UV-A SEOFs upregulated quorum sensing, surface attachment, and oxidative stress genes, resulting in higher extracellular polymeric substances (EPS) accumulation on membrane surfaces. Overall, SEOFs that deliver a low fluence of UV-C light onto membrane surfaces are a promising non-chemical approach for mitigating biofouling formation on RO membranes.

In situ chemical oxidation of contaminated groundwater using a sulfidized nanoscale zerovalent iron-persulfate system: Insights from a box-type study.

We report the potential of a sulfidized nanoscale zerovalent iron-persulfate (S-nZVI-PS) system for in situ chemical oxidation (ISCO) of groundwater pollutants. The study was conducted using a sand-filled rectangular box with a permeable reactive barrier of S-nZVI as a facsimile of the ISCO system. Synthetic water contaminated with a target pollutant (reactive black-5, RB-5) was continuously passed through the box. The injection of PS led to the complete removal of RB-5 and the system remained reactive for approximately 12 days. This system has a benefit that the oxidation products of S-nZVI (i.e., Fe3O4, Fe2O3, and FeSO4) can further activate PS to retain its reactivity. In a separate trial, this method exploited oxidation, reduction, adsorption and co-precipitation mechanisms that conspired to remove two different groundwater pollutants- arsenite and 1,4-dioxane. These results confirmed the utility of S-nZVI-PS as a mediator of ISCO processes to degrade groundwater pollutants.

Surveillance Rate and its Impact on Survival of Hepatocellular Carcinoma Patients in South Korea: A Cohort Study.

PURPOSE: Though regular surveillance of hepatocellular carcinoma (HCC) for high-risk patients is widely recommended, its rate and effectiveness are not clear. The aim of this study is to investigate the actual rate of HCC surveillance and its related factors and to clarify its impact on survival in a Korean HCC cohort. MATERIALS AND METHODS: From 2012 to 2015, 319 newly diagnosed HCC patients were prospectively enrolled at a tertiary hospital. Patient interviews based on a structured questionnaire survey were conducted. Surveillance was defined as liver imaging test ≥ 2 times with at least 3-month interval within 2 years prior to HCC diagnosis. RESULTS: Surveillance rate was 39.8%. Of the HCC patients with high-risk factors, only 182 (57.1%) had knowledge for the need for regular surveillance, and 141 (44.2%) had the accurate information about the method (ultrasound-based study). Surveillance group showed a higher proportion of early HCC (p < 0.001) and a longer overall survival (p < 0.001) compared to non-surveillance group. The multivariable Cox regression analysis indicated Child-Pugh class A, history of anti-viral therapy, low serum α-fetoprotein level, non-advanced Barcelona Clinic Liver Cancer stage as independent predictors of overall survival, while regular surveillance was not (p=0.436). CONCLUSION: Less than half of the newly diagnosed Korean HCC patients were under surveillance and the accurate perception for the need of HCC surveillance was insufficient. Of those under surveillance, most patients were diagnosed with early stage HCC, which led to the improved survival. Comprehensive efforts to optimize the surveillance program for the target population are warranted.

Liver volume-based prediction model stratifies risks for hepatocellular carcinoma in chronic hepatitis B patients on surveillance.

BACKGROUND AND AIM: The aim of this study was to determine whether dynamic computed tomography (CT)-measured liver volume predicts the risk of hepatocellular carcinoma (HCC) when the CT scans do not reveal evidence of HCC in chronic hepatitis B (CHB) patients on surveillance. METHODS: This retrospective multicentre cohort study included 1,246 patients who received entecavir and regular HCC surveillance in three tertiary referral centres in South Korea. Liver volumes were measured on portal venous phase CT images. A nomogram was developed based on Cox independent predictors and externally validated. Time-dependent receiver operating characteristic (ROC) analysis was performed for comparison with previous prediction models. RESULTS: Patients who received dynamic CT studies during surveillance had significantly higher risk for HCC compared to patients without CT studies (hazard ratio [HR] = 3.1; p < 0.001). Expected/measured liver volume ratio was an independent predictor of HCC (HR = 4.2; p = 0.002) in addition to age, sex and cirrhosis. The nomogram based on the four predictors discriminated risks for HCC (HR = 4.1 and 6.0 in derivation and validation cohort, respectively, for volume score > 150; p < 0.001). Time-dependent ROC analysis confirmed better performance of the volume score compared to HCC prediction models with conventional predictors (integrated area under curve = 0.758 vs. 0.661-0.712; p < 0.05). CONCLUSIONS: CT-measured liver volume is an independent predictor of future HCC, and nomogram-based liver volume score may stratify the risks of HCC in CHB patients who showed negative CT findings for HCC during surveillance.

Optimizing Surveillance Performance of Alpha-Fetoprotein by Selection of Proper Target Population in Chronic Hepatitis B.

Although alpha-fetoprotein (AFP) is the most widely used biomarker in hepatocellular carcinoma (HCC) surveillance, disease activity may also increase AFP levels in chronic hepatitis B (CHB). Since nucleos(t)ide analog (NA) therapy may reduce not only HBV viral loads and transaminase levels but also the falsely elevated AFP levels in CHB, we tried to determine whether exposure to NA therapy influences AFP performance and whether selective application can optimize the performance of AFP testing in CHB during HCC surveillance. A retrospective cohort of 6,453 CHB patients who received HCC surveillance was constructed from the electronic clinical data warehouse. Covariates of AFP elevation were determined from 53,137 AFP measurements, and covariate-specific receiver operating characteristics regression analysis revealed that albumin levels and exposure to NA therapy were independent determinants of AFP performance. C statistics were largest in patients with albumin levels ≥ 3.7 g/dL who were followed without NA therapy during study period, whereas AFP performance was poorest when tested in patients with NA therapy during study and albumin levels were < 3.7 g/dL (difference in C statics = 0.35, p < 0.0001). Contrary to expectation, CHB patients with current or recent exposure to NA therapy showed poorer performance of AFP during HCC surveillance. Combination of concomitant albumin levels and status of NA therapy can identify subgroup of CHB patients who will show optimized AFP performance.

Hypercholesterolemia and in-vivo coronary plaque composition in patients with coronary artery disease: a virtual histology - intravascular ultrasound study.

BACKGROUND AND OBJECTIVES: Hypercholesterolemia is a key factor in the development of atherosclerosis. We sought to evaluate the relation between hypercholesterolemia and plaque composition in patients with coronary artery disease. SUBJECTS AND METHODS: Study subjects consisted of 323 patients (mean 61.5 years, 226 males) who underwent coronary angiography and virtual histology-intravascular ultrasound examination. Patients were divided into two groups according to total cholesterol level: hypercholesterolemic group (≥200 mg/dL, n=114) and normocholesterolemic group (<200 mg/dL, n=209). RESULTS: Hypercholesterolemic patients were younger (59.7±13.3 years vs. 62.6±11.5 years, p=0.036), than normocholesterolemic patients, whereas there were no significant differences in other demographics. Hypercholesterolemic patients had higher corrected necrotic core volume (1.23±0.85 mm(3)/mm vs. 1.02±0.80 mm(3)/mm, p=0.029) as well as percent necrotic core volume (20.5±8.5% vs. 18.0±9.2%, p=0.016) than normocholesterolemic patients. At the minimal lumen area site, percent necrotic core area (21.4±10.5% vs. 18.4±11.3%, p=0.019) and necrotic core area (1.63±1.09 mm(2) vs. 1.40±1.20 mm(2), p=0.088) were also higher than normocholesterolemic patients. Multivariate linear regression analysis showed that total cholesterol level was an independent factor of percent necrotic core volume in the culprit lesion after being adjusted with age, high density lipoprotein-cholesterol , hypertension, diabetes mellitus, smoking and acute coronary syndrome (beta 0.027, 95% confidence interval 0.02-0.053, p=0.037). CONCLUSION: Hypercholesterolemia was associated with increased necrotic core volume in coronary artery plaque. This study suggests that hypercholesterolemia plays a role in making plaque more complex, which is characterized by a large necrotic core, in coronary artery disease.