Effects and safety of virtual reality-based mindfulness in patients with psychosis: a randomized controlled pilot study.

Virtual reality (VR) technology can be a supporting tool to enhance mindfulness. Recently, many research using VR-based mindfulness (VBM) has been carried out in various psychiatric disorders but not in psychosis. We investigated safety and effects of virtual reality-based mindfulness (VBM) in patients with psychosis as a pilot study. Sixty-four patients were randomly assigned to VBM or to VR control. For VBM, education and meditation videos were provided. For VR control, 3-dimensional natural scenes were shown. Both programs consisted of 8 weekly sessions, each lasting about 30 min. Pre- and post-assessments were performed using the experiences questionnaire (EQ), psychotic symptom rating scales-delusion (PSYRATS-D), PSYRATS-auditory hallucinations (AH), motivation and pleasure scale-self rating (MAP-SR) and etc. The safety questionnaire was also surveyed after 1st and 8th session. Physiological measures such as skin conductance level (SCL), heart rate (HR) and RR interval, were collected during the VR interventions. Limited individuals participated in the safety questionnaire and physiological measures. All the results were presented in mean and standard deviation. We did not observe significant results in group x time interaction and main effects of group and time in the decentering and clinical scales. However, within group comparison showed that patients randomized to VBM showed increased decentering (p = 0.029) and decreased amount (p = 0.032) and duration of preoccupation (p = 0.016) in the PSYRATS-D. For the feelings and motivations about close caring relationships of the MAP-SR, we observed a significant group x time interaction (p = 0.027). The frequency of VR sickness was high but its severity was mild. There were significant differences only in HR over time in the VBM group (p = 0.01). These results suggest that VBM was not more effective in reducing decentering and psychiatric symptoms than VR control but its adversity was modest.

Improving algal bloom detection using spectroscopic analysis and machine learning: A case study in a large artificial reservoir, South Korea.

The prediction of algal blooms using traditional water quality indicators is expensive, labor-intensive, and time-consuming, making it challenging to meet the critical requirement of timely monitoring for prompt management. Using optical measures for forecasting algal blooms is a feasible and useful method to overcome these problems. This study explores the potential application of optical measures to enhance algal bloom prediction in terms of prediction accuracy and workload reduction, aided by machine learning (ML) models. Compared to absorption-derived parameters, commonly used fluorescence indices such as the fluorescence index (FI), humification index (HIX), biological index (BIX), and protein-like component improved the prediction accuracy. However, the prediction accuracy was decreased when all optical indices were considered for computation due to increased noise and uncertainty in the models. With the exception of chemical oxygen demand (COD), this study successfully replaced biochemical oxygen demand (BOD), dissolved organic carbon (DOC), and nutrients with selected fluorescence indices, demonstrating relatively analogous performance in either training or testing data, with consistent and good coefficient of determination (R2) values of approximately 0.85 and 0.74, respectively. Among all models considered, ensemble learning models consistently outperformed conventional regression models and artificial neural networks (ANNs). However, there was a trade-off between accuracy and computation efficiency among the ensemble learning models (i.e., Stacking and XGBoost) for algal bloom prediction. Our study offers a glimpse of the potential application of spectroscopic measures to improve accuracy and efficiency in algal bloom prediction, but further work should be carried out in other water bodies to further validate our proposed hypothesis.

Weekend effect on 30-day mortality for ischemic and hemorrhagic stroke analyzed using severity index and staffing level.

BACKGROUND AND PURPOSE: Previous studies on the weekend effect-a phenomenon where stroke outcomes differ depending on whether the stroke occurred on a weekend-mostly targeted ischemic stroke and showed inconsistent results. Thus, we investigated the weekend effect on 30-day mortality in patients with ischemic or hemorrhagic stroke considering the confounding effect of stroke severity and staffing level. METHODS: We retrospectively analyzed data of patients hospitalized for ischemic or hemorrhagic stroke between January 1, 2015, and December 31, 2018, which were extracted from the claims database of the National Health Insurance System and the Medical Resource Report by the Health Insurance Review & Assessment Service. The primary outcome measure was 30-day all-cause mortality. RESULTS: In total, 278,632 patients were included, among whom 84,240 and 194,392 had a hemorrhagic and ischemic stroke, respectively, with 25.8% and 25.1% of patients, respectively, being hospitalized during the weekend. Patients admitted on weekends had significantly higher 30-day mortality rates (hemorrhagic stroke 16.84%>15.55%, p<0.0001; ischemic stroke 5.06%>4.92%, p<0.0001). However, in the multi-level logistic regression analysis adjusted for case-mix, pre-hospital, and hospital level factors, the weekend effect remained consistent in patients with hemorrhagic stroke (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.00-1.10), while the association was no longer evident in patients with ischemic stroke (OR 1.01, 95% CI 0.96-1.06). CONCLUSIONS: Weekend admission for hemorrhagic stroke was significantly associated with a higher mortality rate after adjusting for confounding factors. Further studies are required to understand factors contributing to mortality during weekend admission.

Temporal and spatial distribution of microplastic in the sediment of the Han River, South Korea.

Sediments are sinks for microplastics (MPs) in freshwater environments. It is, therefore, necessary to investigate the occurrence and fate of accumulated MPs in the sediments, which pose a risk to aquatic organisms. We conducted the first comprehensive investigation of MPs in riverine sediment in South Korea to examine the temporal and spatial distribution of MPs in the sediment at the two main branches and downstream of the Han River. The average abundance of MPs over all sites was 0.494 ± 0.280 particles/g. Spatially, the MP abundance at three sites in the North Han River (0.546 ± 0.217 particles/g) was higher than those in the South Han River (0.383 ± 0.145 particles/g) and downstream of the Han River (0.417 ± 0.114 particles/g). The abundances of MPs before dams at two upstream sites were significantly higher than that at other sites because of the slow river flow velocity attributed to the artificial structure. The abundance of MPs after the mosoon season (October, 0.600 ± 0.357 particles/g) was higher than that before the mosoon season (April, 0.389 ± 0.099 particles/g). The most common polymer types observed were polyethylene (>38%) and polypropylene (>24%). Irrespective of the location and season, greater than 93% of MPs identified were fragments, and the remaining were fibers. The concentrations of TOC, TN, and TP in the sediment were positively correlated with MP abundance. MP abundance was also positively correlated with clay and silt fractions of the sediment; however, it was negatively correlated with sand fraction. This study provides a basis for the management of MP pollution by offering findings related to critical factors influencing MP abundance in sediment.

Predictors of full recovery in patients with early stage schizophrenia spectrum disorders.

To promote recovery in psychosis, targeting modifiable factors related to recovery is critical. Using more strict definition of full recovery, we examined predictors for recovery in patients with early stage schizophrenia spectrum disorders (SSD) followed up to 6.5 years. The target subjects were 375 patients with early stage SSD who had been over at least 1-year after registration and evaluated. The criteria for full recovery were having the score of the Positive and Negative Syndrome Scale (PANSS) 8-item ≤ 2 and adequate functional recovery for at least 1-year. We performed univariate Cox and stepwise Cox regression in both total and acute patients. In stepwise Cox regression, several independent predictors for recovery, i.e., negative symptoms of the PANSS, duration of untreated psychosis (DUP) and non-professional job were identified in patients with early stage SSD. In acute patients, other factors such as professional job and subjective well-being under neuroleptics were more important. The present study identified independent predictors for recovery modifiable by various psychosocial intervention and early intervention services. Moreover, it highlights the need of providing different treatment strategies depending on clinical status.

Three-year outcomes and predictors for full recovery in patients with early-stage psychosis.

In the present study, various outcomes over 3-year period in patients with early stage psychosis including remission, recovery, relapse and medication adherence were investigated. Predictor for full recovery at year 3 was also examined. Three-year follow-up data in 534 patients with schizophrenia spectrum disorders (SSD) and psychotic disorder not otherwise specified (PNOS) were examined for overall outcome trajectories. The data of completers at year 3 (n = 157) were used to identify predictors for recovery using logistic regression. The rates of symptomatic remission and full recovery at 6-, 12-, 24-, and 36-month follow-up were 76.10, 69.20, 79.50, and 79.10%, and 22.80, 26.40, 28.60, and 39.60%, respectively. The rates of drop-out and relapse at 6-, 12-, 24-, and 36-month follow-up were 25.4, 29.5, 38.6, and 51.1%, and 3.7, 8.9, 19.0, and 38.9%, respectively. The rates of good adherence and prescription of Long-Acting Injectable Antipsychotics (LAIA) at 6-, 12-, 24- and 36-month follow-up were 87.8, 88.0, 91.9, and 93.9%, and 18.3, 21.7, 22.0, and 25.5%, respectively. Significant predictors for full recovery were duration of untreated psychosis (DUP), family intimacy and physical activity. We observed similar or better results on remission, recovery, and relapse rates compared to other previous studies. Effective psychosocial intervention should be provided to shorten the gap between remission and recovery rates and to address DUP, family issues, and exercise to enhance recovery.

Comparison of clinical features and 1-year outcomes between patients with psychotic disorder not otherwise specified and those with schizophrenia.

AIM: Research on psychotic disorder not otherwise specified (PNOS) that clearly mentions its subgroups is very rare. This study was conducted to identify the demographic and clinical features, cognitive function, and 1-year outcomes of patients with early stage PNOS compared with those with early stage schizophrenia (SZ). METHODS: The study subjects were 54 and 321 patients with PNOS and SZ, respectively, who were registered at least more than 1 year ago. Due to drop out, only 37 and 210 patients with PNOS and SZ were evaluated at the 1-year follow-up. We compared clinical variables (duration of untreated psychosis, symptom severity, self-rating scales, and so on), cognitive function, and short-term outcomes (treatment response, remission, compliance, drop out, relapse) between the two groups. RESULTS: The patients with PNOS were associated with higher diagnostic stability (53.7%) compared with those in previous studies. They had lower symptom severity, better treatment response at 2 months and higher remission rates at 12 months, but poorer compliance at 6 months compared with patients with SZ. Level of cognitive impairment in PNOS was intermediate between those of SZ patients and healthy controls. CONCLUSIONS: These findings indicate that PNOS has unique clinical features, suggesting that it should be treated as a distinct clinical syndrome. At the same time, however, prevention of its possible progression to other psychotic disorders in some patients with PNOS is also important.

The effects of the molecular weights of hyaluronic acid on the immune responses.

BACKGROUND: The molecular weight of hyaluronic acid (HyA) depends on the type of organ in the body. When HyA of the desired molecular weight is implanted into the human body for regeneration of damaged tissue, it is degraded by hyaluronidase in associated with an inflammatory response. This study sought to evaluate the effects of HyA molecular weight and concentration on pro- and anti-inflammatory responses in murine macrophages. METHODS: The structures and molecular weights of HyAs (LMW-10, MMW-100, MMW-500, and HMW-1,500) were confirmed by 1 H NMR and gel permeation chromatography (GPC), respectively. After treatment of murine macrophages with a low (10 µg/mL) or high (100 µg/mL) concentration of each molecular weight HyA, cells were stimulated with lipopolysaccharide (LPS) and changes in immune response in both LPS-stimulated and untreated macrophages were evaluated by assessing nitric oxide (NO) production, and analyzing expression of pro- and anti-inflammatory genes including by RT-PCR. RESULTS: Molecular weights of LMW-10, MMW-100, MMW-500, and HMW-1,500 were 13,241 ± 161, 96,531 ± 1,167, 512,657 ± 8,545, and 1,249,500 ± 37,477 Da, respectively. NO production by LPS-stimulated macrophages was decreased by increasing concentrations and molecular weights of HyA. At a high concentration of 100 µg/mL, HMW-1,500 reduced NO production in LPS-stimulated macrophages to about 45 %. Using NanoString technology, we also found that the immune-related genes TNF-α, IL-6, IL-1ß, TGF-ß1, IL-10, IL-11, CCL2, and Arg1 were specifically over-expressed in LPS-stimulated macrophages treated with various molecular weights of HyA. An RT-PCR analysis of gene expression showed that HMW-1,500 decreased expression of classically activated (M1) macrophage genes, such as TNF-α, IL-6, CCL2, and IL-1ß, in LPS-stimulated macrophages, whereas medium molecular-weight HyA (MMW-100 and MMW-500) instead increased expression levels of these genes. HMW-1,500 at a high concentration (100 µg/mL) significantly decreased expression of pro-inflammatory genes in LPS-stimulated macrophages. Expression of genes associated with anti-inflammatory responses (M2 phenotype), such as TGF-ß1, IL-10, IL-11, and Arg1, were increased by high concentrations of MMW-500 and HMW-1,500 in LPS-stimulated macrophages. CONCLUSIONS: High molecular-weight HyA (i.e., > 1,250 kDa) inhibits pro-inflammatory responses in LPS-stimulated macrophages and induces anti-inflammatory responses in a concentration dependent manner.

Unique Metabolic Profiles of Korean Rice According to Polishing Degree, Variety, and Geo-Environmental Factors.

The precise determination of the chemical composition in crops is important to identify their nutritional and functional value. The current study performed a systematic delineation of the rice metabolome, an important staple in Asia, to investigate the following: (1) comparative features between brown and white rice; (2) variety-specific composition (Ilpum vs. Odae); and (3) cultivation of region-dependent metabolic content. Global metabolic profiling and data-driven statistics identified the exclusive enrichment of compounds in brown rice compared to white rice. Next, the authors investigated a variety-governed metabolic phenotype among various geo-environmental factors. Odae, the early-ripening cultivar, showed higher contents of most chemicals compared to the late-ripening cultivar, Ilpum. The authors identified regional specificity for cultivation among five areas in Korea which were characterized by polishing degree and cultivar type. Finally, the current study proposes a possible linkage of the region-specific metabolic signatures to soil texture and total rainfall. In addition, we found tryptophan metabolites that implied the potential for microbe-host interactions that may influence crop metabolites.

Identification of quantitative trait loci associated with flowering time in perilla using genotyping-by-sequencing.

Understanding the transition to the reproductive period is important for crop breeding. This information can facilitate the production of novel varieties that are better adapted to local environments or changing climatic conditions. Here, we report the development of a high-density linkage map based on genotyping-by-sequencing (GBS) for the genus perilla. Through GBS library construction and Illumina sequencing of an F2 population, a total of 9607 single-nucleotide polymorphism (SNP) markers were developed. The ten-group linkage map of 1309.39 cM contained 2518 markers, with an average marker density of 0.56 cM per linkage group (LG). Using this map, a total of six QTLs were identified. These quantitative trait loci (QTLs) are associated with three traits related to flowering time: days to visible flower bud, days to flowering, and days to maturity. Ortholog analysis conducted with known genes involved in the regulation of flowering time among different crop species identified GI, CO and ELF4 as putative perilla orthologs that are closely linked to the QTL regions associated with flowering time. These results provide a foundation that will be useful for future studies of flowering time in perilla using fine mapping, and marker-assisted selection for the development of new varieties of perilla.

Highly geographical specificity of metabolomic traits among Korean domestic soybeans (Glycine max).

Classification and characterization of agricultural products at molecular levels are important but often impractical with genotyping, particularly for soybeans that have numerous types of variety and landraces. Alternatively, metabolic signature, a determinant for nutritional value, can be the good molecular indicator, which reflects cultivation region-dependent factors such as climate and soil. Accordingly, we analyzed the integrative metabolic profiles of Korean soybeans cultivated in 7 different provinces (representative production areas), and explored the potential association with geographic traits. A total of 210 primary and secondary metabolites were profiled using gas-chromatography time-of-flight mass spectrometry (GC-TOF MS) and liquid-chromatography Orbitrap mass spectrometry (LC-Orbitrap MS). Despite the partial heterogeneity of the soybean varieties, the metabolomic phenotypic analysis based on multivariate statistics inferred the chemical compositional characteristics was primarily governed by the regional specificity. The OPLS-DA model proposed biomarker cluster re-composed with 5 metabolites (tryptophan, malonylgenistin, malonyldaidzin, N-acetylornithine, and allysine) (AUCs = 0.870-1.0). The most distinctive metabolic profiles were identified with the soybeans of Gunsan (middle-western coast) and Daegu (east-southern inland area), which were best characterized by the highest contents of isoflavones and amino acids, respectively. Further interrogation on geographic data suggested the combinatorial association of region-specific metabolic features with general soil texture and climate traits (total rainfall and average annual temperature).

Lignans from Saururus chinensis exhibit anti-inflammatory activity by influencing the Nrf2/HO-1 activation pathway.

As part of our ongoing program to develop anti-inflammatory agents, an extract derived from Saururus chinensis collected in Korea was found to inhibit nitric oxide (NO) production in RAW264.7 cells. Bioassay-guided fractionation led to the isolation two new (1 and 2) and six known dineolignans (3-8). To the best of our knowledge, manassatin B1 (3) was isolated from S. chinensis for the first time. All structures were elucidated using extensive spectroscopic analysis. Of these compounds, 2 and 8 inhibited lipopolysaccharide (LPS)-induced production of NO and showed IC50 values of 5.80 and 1.52 µM, respectively. LPS-induced expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) was also significantly suppressed by the administration of 2 and 8. In addition, these lignans induced the expression of heme oxygenase-1 (HO-1) in a concentration-dependent manner. Nuclear translocation of nuclear-E2-related factor 2 (Nrf2), a key regulator of HO-1 protein expression, was also induced in RAW264.7 cells treated with 2 and 8. These findings suggested that these lignans exerted anti-inflammatory effects in RAW264.7 cells through modulation of the Nrf2/HO-1 pathway and that they were potential HO-1 inducers for preventing or treating inflammation.

Triterpenoids from Ziziphus jujuba induce apoptotic cell death in human cancer cells through mitochondrial reactive oxygen species production.

Ziziphus jujuba var. inermis Rehder is an edible fruit-producing species of the Rhamnaceae family. In the present study, we isolated eight triterpenoids (1-8) from the fruits of Z. jujuba var. inermis and evaluated their apoptotic cell-death-inducing activities in human cancer cell lines (A549, PC-3, and MDA-MB-231). The structures of compounds 1-8 were determined by spectroscopic methods. Among these, four isomers of coumaroyl alphitolic acid showed potent cytotoxic activities on these cancer cells: 3-O-cis-p-coumaroyl alphitolic acid (3), 3-O-trans-p-coumaroyl alphitolic acid (4), 2-O-trans-p-coumaroyl alphitolic acid (5), and 2-O-cis-p-coumaroyl alphitolic acid (6). Moreover, compounds 3-6 induced apoptotic cell death in a concentration-dependent manner. We further investigated the apoptosis-inducing effects of compound 4 in PC-3 cells which triggered the cleavage of procaspase-3, procaspase-7, procaspase-8, bid, and PARP. Compound 4 increased both the mitochondrial reactive oxygen species (ROS) production and the phosphorylation of p38 MAPK (mitogen-activated protein kinase), but decreased the mitochondrial membrane potential. Pretreatment with Mito-TEMPO (a specific mitochondrial-targeted antioxidant) or a specific p38 inhibitor (SB203580) attenuated apoptotic cell death triggered by compound 4 which suggests that compound 4 may induce apoptotic cell death in these cancer cells by increasing the mitochondrial ROS production as well as the subsequent p38 MAPK activation. The study findings provide a rational base to use Ziziphus extracts for cancer treatments in traditional oriental medicine.

Carbon nanotube thin film strain sensors: comparison between experimental tests and numerical simulations.

Carbon nanotubes can be randomly deposited in polymer thin film matrices to form nanocomposite strain sensors. However, a computational framework that enables the direct design of these nanocomposite thin films is still lacking. The objective of this study is to derive an experimentally validated and two-dimensional numerical model of carbon nanotube-based thin film strain sensors. This study consisted of two parts. First, multi-walled carbon nanotube (MWCNT)-Pluronic strain sensors were fabricated using vacuum filtration, and their physical, electrical, and electromechanical properties were evaluated. Second, scanning electron microscope images of the films were used for identifying topological features of the percolated MWCNT network, where the information obtained was then utilized for developing the numerical model. Validation of the numerical model was achieved by ensuring that the area ratios (of MWCNTs relative to the polymer matrix) were equivalent for both the experimental and modeled cases. Strain sensing behavior of the percolation-based model was simulated and then compared to experimental test results.

Cytotoxic Activity of Compounds from Styrax obassia.

Cancer is a major public health burden in both developed and developing countries. Plant-derived compounds have played an important role in the development of useful anti-cancer agents. The current study was designed to evaluate the cytotoxic activity of chemical compounds from the stem bark of Styrax obassia. Seven known compounds (1-7) were isolated and identified. Compound 2 exhibited cytotoxic activity against the breast cancer cell line MCF-7 with an IC550 of 27.9 µM, followed by the human cervical cancer cell line Hela with an IC50 of 23.3 µM, and the human promyelocytic leukemia cell line HL-60 with an IC50 of 47.8 RM. Compound 7 exhibited cytotoxicity against Hela cells with an ICso of 16.8 pM, followed by MCF-7 cells with an IC50 of 53.5 µM. This is the first study to investigate the significant anti-tumor properties of isolated compounds from the stem bark of S. obassia.

Adsorption Behavior of Extracellular Polymeric Substances on Graphene Materials Explored by Fluorescence Spectroscopy and Two-Dimensional Fourier Transform Infrared Correlation Spectroscopy.

Adsorption isotherms of extracellular polymeric substances (EPS) on graphene oxide (GO) and reduced GO (rGO) were studied using fluorescence excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2D-COS) combined with Fourier transform infrared spectroscopy (FTIR). Chemical reduction of GO resulted in a greater extent of carbon adsorption with a higher degree of isotherm nonlinearity, suggesting that heterogeneous adsorption sites were additionally created by GO reduction. Two protein-like and two humic-like components were identified from EPS by EEM-PARAFAC. Adsorption of protein-like components was greater than that of humic-like components, and the preferential adsorption was more pronounced for GO versus rGO. Adsorption of protein-like components was more governed by site-limiting mechanisms than humic-like components as shown by the higher isotherm nonlinearity. 2D-COS provided further information on the adsorption of secondary protein structures. Adsorption of the EPS structures related to amide I and aromatic C-C bands was greater for rGO versus GO. Protein structures of EPS were more favorable for adsorption in the order of α-helix → amide II → ß-sheet structures with increasing site limitation. Our results revealed successful applicability of EEM-PARAFAC and 2D-COS in examining the adsorption behavior of heterogeneous biological materials on graphene materials.

Effect of Bulky and Hydroxyl Groups on Gas Separation Performance of Polyimide Membranes.

A series of polyimides were synthesized by a polycondensation reaction using various aromatic dianhydrides and diamines containing bulky cardo and hydroxyl groups. The imidization and chemical structure of the polyimides were confirmed by NMR and FT-IR. The thermal and gas properties of the polyimides were measured by time-lag, XRD, TGA, and DSC studies. The polyimides showed excellent solubility in common organic solvents and high thermal stability. The CO2 selectivity of HPI membrane was higher than traditional polyimides. In particular, the incorporation of hydroxyl groups improved the CO2 permeability of the polyimide due to increased carbon dioxide solubility. The HPI was thermally converted to polybenzoxazole (PBO) at 450 °C.

Topical application of a cleanser containing extracts of Diospyros kaki folium, Polygonum cuspidatum and Castanea crenata var. dulcis reduces skin oil content and pore size in human skin.

The effects of skin pores on skin topographic features can be reduced by decreasing excessive production and accumulation of sebum and elimination of comedones. Therefore, a cosmetic cleanser that regulates sebum homeostasis is required. In the present study, the effects of a cosmetic cleanser that contained Diospyros kaki folium, Polygonum cuspidatum and Castanea crenata var. dulcis (DPC) was examined on the removal of sebum and on skin pore size. Healthy volunteers (n=23) aged 20-50 years were asked to apply the test materials to the face. Skin oil content, pore size, pore number and extracted sebum surface area were measured using various measurement methods. All the measurements were performed at pre- and post-application of the test materials. When the cosmetic cleanser containing DPC was applied to the skin, the oil content decreased by 77.3%, from 6.19 to 1.40. The number of skin pores decreased by 24.83%, from 125.39 to 94.23. Skin pore size decreased from 0.07 to 0.02 µm3 (71.43% decrease). The amount of extracted sebum increased by 335% when the DPC cleanser was used. Compared to the control cleanser, skin oil content was significantly decreased when the cleanser that contained DPC was used. The cleanser containing DPC also decreased pore size and number. Finally, the DPC cleanser easily removed solidified sebum from the skin.

Characterizing treated wastewaters of different industries using clustered fluorescence EEM-PARAFAC and FT-IR spectroscopy: implications for downstream impact and source identification.

The quantity and spectroscopic features of dissolved organic matter (DOM) in treated wastewaters were studied for up to 57 facilities across 12 industrial categories to evaluate the potential influences of the effluents on downstream ecosystems and the feasibility of spectroscopic techniques in discriminating pollution sources. The average dissolved organic carbon (DOC) concentration was 3.30±0.70-73.4±14.0 mg L(-1) for each category, high enough to pollute downstream waterbodies. The average specific UV absorbance at 254 nm (SUVA) for each category spanned a broad range between 0.79±0.24 and 5.35±1.41 L(mg m)(-1), suggesting a variable aromaticity of DOM. Fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC) identified four humic-like and two protein-like components. The EEMs were grouped into seven clusters, five of which were dominated by a single PARAFAC component in each cluster. Fourier transform infrared (FT-IR) spectroscopy revealed notable variations in relative intensities of several characteristic absorbance bands among different wastewaters. The large variability in SUVA, PARAFAC and FT-IR features indicated that the chemical composition of DOM greatly differ among industrial wastewaters, and further implied variable biogeochemical reactivity in downstream waterbodies. The results also suggested the potential of DOM features in discriminating different wastewaters, although the variations within each industrial category were also significant.

Investigation of adsorptive fractionation of humic acid on graphene oxide using fluorescence EEM-PARAFAC.

In this study, the adsorptive fractionation of a humic acid (HA, Elliott soil humic acid) on graphene oxide (GO) was examined at pH 4 and 6 using absorption spectroscopy and fluorescence excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC). The extent of the adsorption was greater at pH 4.0 than at pH 6.0. Aromatic molecules within the HA were preferentially adsorbed onto the GO surface, and the preferential adsorption was more pronounced at pH 6, which is above the zero point of charge of GO. A relative ratio of two PARAFAC humic-like components (ex/em maxima at 270/510 nm and at (250, 265)/440 nm) presented an increasing trend with larger sizes of ultrafiltered humic acid fractions, suggesting the potential for using fluorescence EEM-PARAFAC for tracking the changes in molecular sizes of aromatic HA molecules. The individual adsorption behaviors of the two humic-like components revealed that larger sized aromatic components within HA had a higher adsorption affinity and more nonlinear isotherms compared to smaller sized fractions. Our results demonstrated that adsorptive fractionation of HA occurred on the GO surface with respect to their aromaticity and the sizes, but the degree was highly dependent on solution pH as well as the amount of adsorbed HS (or available surface sites). The observed adsorption behaviors were reasonably explained by a combination of different mechanisms previously suggested.